I should probably acknowledge this is a contentious topic, and I tend to lean towards the lower power level than some. That said, what do those higher levels mean? For your most important skills, 15 levels means 30-35 ranks (depending on TPs and cultures) which is bonuses (for standard progression skills) of at least +95. Throw in a profession bonus of +10 and assume a stat bonus of, say, +10, which is conservative since an RMSS character at 15th level will have hit all their potentials. Add up to +15 for background options. You're now at +130.
What does it mean to have a skill bonus of +130? It means that a task characterized as "medium" difficulty is trivial for you, you only need to roll a -19 or better (an open-ended down roll) for a complete success, and in many cases a -54 is good enough. You achieve an absolute success on a 46 or higher, so you achieve an absolute success more than half the time. For tasks that are Sheer Folly, you still need to roll an open-ended down roll to outright fail -- you are more likely to achieve absolute success on a Sheer Folly task than you are to suffer even a regular failure.
What sorts of things might you be routinely achieving on that basis? Depending on the skill you might be swinging from one rope to catch another rope 25' away, impersonating people to their own close family and friends, camouflaging things the size of a house, climbing 120 degree (i.e. you're upside down) smooth surfaces, negotiating deals where all concessions are made by the other party, diving off a bridge onto a moving horse, convincing someone to do something harmful like drinking a glass of acid, creating forgeries that cannot be detected without scientific or magical testing, throwing dice so you decide how they come up, hypnotically persuading someone to commit murder, juggling 9 objects, running long jump of 24 feet (based on average height and +7 St including the racial mod), maintaining morale after suffering 75% casualties, memorizing entire novels, etc. And, again, these are not just things you have occasionally pulled off but things that you almost always succeed at without any special preparation or quality tools, and are more likely to achieve some kind of additional (absolute) success as you are to fail.
I just don't think most people ever achieve those kinds of abilties in their lives. Those are the kinds of achievements that a person might reach if they train intensively and constantly push themselves. They aren't the kind of achievements of people who just go about their daily routines day after day. I think the latter group will be lucky to reach half that kind of skill bonus. And a bonus of +65 in RMSS is something you can easily reach around 5th level, sooner if you have training packages or a culture that includes those skills.