I don't agree with this assessment.
The fighter only has to get one rank in a spell list and they can use that spell at their FULL LEVEL of ability. Like my 7th level fighter using Shadow, gets to have that spell going for 7 minutes - from a single rank. The mage on the other hand, gets a single rank in a weapon skill and they get what, a +3 or +5 for RMSS/FRP or RM1/2/C, respectively. (Not including the dropping of the -15 or -25 when not having the skill.) To have all the versatility they can get from magic a mage needs to purchase a lot of ranks in a wide variety of spell lists, quite the DP sink, and much harder to do if they are spending 9 DP/level on weapon skills - or more.
Please, don't misunderstand me here; I don't think a fighter (or any pure-arms profession) will be able to cast spells like a mage, because they won't. But I do believe, that a fighter can keep their usefulness, and playability enjoyment factor, by just grabbing a few spells and a couple of ranks in PP development.
In RM it becomes a matter of DP expended for benefit gained and the issue of diminishing returns.
Take a Fighter who has to spend 25DP on a single open spell. A Mage has to spend 4DP on a single open spell. So a factor of a little over 6. A Mage spends only 3 on a BASE spell list, something more powerful. A factor of a little over 8.
Take a Mage who has to spend 9DP on a single weapon skill. A Fighter has to spend 1DP on a single weapon skill. A factor of 9.
That's seems like it should be in the Fighters favor right? But you're taking about a much larger chunk of the Fighters DP being lost on that one purchase. And if the Mage buys four spells the Mage has four options, while the Fighter still only has one: Deal damage to the foe. Also consider the Mage is, comparatively, paying fairly small amounts on Closed and Base lists, things incredibly more expensive for the Fighter. For the Fighter Closed are 40, own realm other Base are 80. For the Mage those are 3 and 8.
Then you have to consider the Fighter can only do one thing with his skill, attack you in melee or maybe at range. His weapon skill can't throw firebolts, turn him invisible, let him fly, create water, heal wounds... the list goes on and on.
At some point the Fighter is thinking: Well, I can spend 6DP to get 1 point of weapon skill (due to diminishing returns) or blow 25DP and get a single spell from an open list (or 40 for closed, or 80 for own base). While the Mage is thinking: I've got a ton of spells, I might as well spend 9DP to develop a weapon (which never increases). Now stack the cost of higher level spells for each and the multiplication hits the Fighter even harder.
And, really, as a Mage, I will
likely develop that 9DP single weapon rank from the start (but that might just be me). That way I'll have the option to pick up a missile weapon for example. While I won't have the +20 prof bonus (a la RMSS) and can't spend more to get the second rank, in the end it will be so much easier to catch up fairly well to the Fighter while the Fighter will struggle just to get just open list spells.
Now, I've played a Rogue - often - and I develop my characters more slowly than others by spreading out my purchasing so I get the most for my DP. That helps a lot in making a well rounded character than is more self-sufficient than most, but when I maxed out most my relevant skills buying spells wasn't really a realistic option aside from a few 1st-5th levle ones maybe and even that would take time, I'd blow most my points to get three ranks of spells that were almost always weaker than the Mages. Fortunately we have a robust rune system we use, so I started focusing in 'quasi-magic' stuff with the Rogue... but that was 17th level. I was already to the point that the Mages and even the Semi's would outshine me other than the fact that I was a meat shield. "Here, let me be your bodyguard."
But beyond all of that, I look at it like Jedi vs. Everyone Else in D6 Star Wars: In the beginning Jedi are weaker because they must take attribute dice for Force skills, thusly dropping their attributes - which are a serious pain to increase btw. Only after they have gone a good ways down the Jedi road do they become serious bad-dudes and dudettes. I think that is a fair trade-off. The same goes for Mages vs. Non-Mages in RM, in the beginning Non-Mages are "tougher" in just about every meaning of the word, but when they get their mojo high enough, Mages rock. I don't see this as a problem, but as a feature. The "perfectly balanced" classes (or professions for RM) comes across to me as too artificial and "gamey." I prefer flavor to gamey, so some variance among the professions is OK.
Anyway, isn't this more about what you want to (or feel like) playing and not what is just the most advantageous to "winning?" I play a fighter when I want to play a fighter, a mage when I want to play a mage, a thief when I want to play a thief, etc...
Now, yes, there are other factors like what all the other skills cost and play-style, but we're talking about characters hitting their early teens and on when it comes to this problem. For a game that has 50th level spells in the core mechanics that has always seemed like a problem to me. We always retired characters in the mid to upper teens (levels 12-17 or so) and started a new campaign (something I'm hoping to change in my campaign). I'd like to see characters fairly equal until at least the mid 20's... and that's one of the things I think RMU is going to partially resolve with profession bonuses being ongoing.
