Back on the first page (and in some follow-ups too) I posted about my (very extensive) RM experience, and what the appeal is. I've never played GURPS, but I think its appeal is pretty close to RM.
But I don't think you can do supers with RM. Or, rather, while the PCs might look superheroes, the stories won't look like superhero comics.
Rolemaster was our game-of-choice for years, across both Second Edition and Standard Edition. The longest running campaign I have ever played in is still a RM campaign. So I am well aware of its strengths and quirks.
Comparing any attempt to run supers with RM versus GURPS is meaningless. The amount of effort needed to get RM like a supers game would be at least one order of magnitude, probably two or even three orders of magnitude larger than running the game in GURPS.
RM is too similar to DnD and, I am sure you will know, originally started off as a set of optional rule systems you could bolt-on to your DnD game. To run supers in DnD you need to make so many changes it basically becomes a completely new game - Mutants & Masterminds. M&M now has so few shared components with DnD OGL it’s a vestigial relationship at most.
GURPS 3e sucked at supers, big time. 3e was a time of rapid expansion for GURPS, and every genre book was standalone, with limited shared design space (yay for the thread topic!). The most egregious example of this was Supers vs Psionics. Both games include psionic powers, but the cost of these powers was at least twice as expensive in Supers. If you tried to mash-up the psychic systems from the two books, any character made with Psionic version would wipe the floor with a Supers version (and throw shade at most other super characters with the same point total, too). This is because the two genre books were created with different baseline assumptions.
GURPS 4e (which is now 15 years old) was written to take all the stuff created across the lifetime of 3e (which itself lasted 16 years), distill it down, find the good stuff and eliminate as much as the rules cruft as possible. Yes, there are still a lot of rules available in GURPS but the vast majority of those rules all exist in the two core books (Characters and Campaigns). The other books provide guidance on
how to use the existing rules to play a game of the type you (the hypothetical ‘you’) are looking for. They may provide more detailed options to increase the emphasis on different aspects, but these are just that - options. There are also ever more books with pre-made materials so that you don’t need to create everything whole-cloth if you are the GM.
Which brings me back to the core question: what is the GURPS design perspective? It is that people want to play different games, and there isn’t a perfect (or even imperfect, in many cases) system already existing that will support those games. And even if there was, why learn a new system with rules that are 70-80% new ways of doing the same thing when you can instead have one system you learn that covers core actions with the same rules and just tops-up with optional rules for the more unique stuff?
Also, since RPGs are about a shared experience and there is an element of chance (as opposed to books etc. where everything runs on author fiat) there needs to be a mechanism to help ensure all players have the same amount of spot light time / game impact. There are several different ways of doing this. GURPS has tried to use a fairly scientific approach as the observable world is the most accessible benchmark we have available. If you like games with strong internal logic, then you will probably find GURPS enjoyable. If you think this kind of stuff gets in the way of having a cool game with your friends then there are other systems which might be a better fit for your needs.
