There are two issues that, to a degree, are at odds with each other.
Obviously bringing the camps together is a stated goal. Pulling the parts of RM2/RMC and RMSS/RMFRP that both groups like, trying to find reasonable modifications to parts that one or the other HATES, and redoing stuff both sides dislike, and leaving alone the stuff that works is obviously the direction that should be taken there. In my opinion this will be difficult. You have to make the system attractive enough for both camps to abandon what they have now (likely their own version they've created over the years) to collectively use the same system now.
It's hard for me to say if this is just a pipe dream or not. We here on these forums are probably more experienced gamers and more hard core RM users. I have a hard time believing ICE will get the buy-in from fans like us until the new system has the variety of material that RMSS or RM2 have. We have our books, we have our home brew version of RM, and many of us are perfectly comfortable pulling bits and pieces from elsewhere and converting it over to RM. It's gonna be a REALLY hard sell to that group. But are we representative of the majority of the existing customer base? That's a hard question to answer.
However, if RM is to survive it needs new customers. More people than not think ICE ceased to exist after the first bankruptcy in my experience. I have not run into a single game store owner in Washington state that didn't think ICE was dead when I initially talked to them - even the ones still with some old ICE products stocked. The second incarnation of ICE really did nothing pro-active to remedy that from what I could tell. At one point they started asking for info on local gaming stores on their forums... but what they needed to do was get off their rear and start doing some research themselves and contacting the major specialized gaming stores in each state to let them know ICE is alive and see if they'd be willing to order a token amount of product just so that it was on the shelves for visibilities sake. If ICE had simply shown up to GenCon - even if they went ultra cheap: drive up, sleep in your car, share a small booth with someone! That would have been the best single one shot advertising they could have given themselves. My point? One of the primary things that was wrong with RM was their marketing efforts - or lack thereof. That needs to change in a big way with the new ICE.
The other problem with getting new customers is RM has endured a fairly negative reputation overall. The reputation is mostly undeserved in my opinion, but the fact remains that it will be a hurdle none the less. Therefore a new version needs to be simplified where at all possible without losing "what is Rolemaster". Opinions on that can vary, but there are some basics that just about every RM user can agree on. So one of the other major things wrong with RM is that it has to overcome it's reputation (deserved or not). Something else that I believe could help here is an effort should possibly be made to compare it to D&D. I really don't understand the "math is hard" criticisms leveled at RM. There really are not many, sometimes even less, rolls made in RM in comparison to D&D and adding up a d100+mods instead of a d20+mods is vastly harder? REALLY? I find that opinion, summed up in a single word, disappointing. It's basic math one more digit out. Stuff like this needs to be pointed out to potential customer and the added flavor (i.e. realism?) needs to go along with that...
...something like...
"D&D: I cast a fireball. [rolls 6d6]. I do XX damage."
"RM: I cast a fireball. [rolls 2d10]. I do XX damage, my foe is knocked to the ground, and is now on fire burning at a rate of 5 hits per round until extinguished."
Which sounds more fun?
But... if you go too simple you start losing some of the core customer base.
As to what is actually wrong with Rolemaster as a system in itself?
There are not many things I consider just plain 'wrong' with Rolemaster, but there are some areas that could use improvement.
I'd like to see how the spell system works modified a bit. I wouldn't want it to go as far as HARP, cause that's far too generic for my tastes, but it would be nice to not see the constant repeating of a certain spell within a list and instead just give a way to increase it's power/strength like HARP does. Professions need to keep their own specialized spell access, that is very important to me. It's a huge part of what makes professions unique.
I have no real problem with the AT system and believe the separation of damage reduction and actual DB is one of the best aspects of RM combat. High armors adding more DB is too simplistic and RM does a far better job of representing armor than systems which do that.
Shields could use some re-doing. This is one of the VERY few areas where some expansion, rather than simplification, is in order.
It would be nice to simplify the attack tables and how they interact with the critical hit charts, but there is a difficult balance of ease of use and acceptable variety.
Separate Race from Culture. Don't think I need to explain that much, but make it possible for a Human to be raised in an Elven society - meaning your Race is Human but your "Adolescence" package is Elven.
For the love of all that is holy dump exhaustion points. Not sure if they even need to be replaced, but it might be possible to come up with an action point system (kinda like a spell casters power points) that would interact with my following point...
Give arms users a reason to continue developing weapon skills. What I'd like to see is a Combat Style system somewhat similar to the Martial Arts Companion expanded to include all Pure Arms Users. Doesn't have to exactly like it, but it needs to grant more benefits as you reach the higher ranks in a weapon or combat maneuver.