I think the difficulty was lowered specifically so that it wouldn't isolate people new to gaming. The wall jumps on both Mario Galaxy and Metroid Prme 3 were made almost infinitely easier than their previous installations.
Spoiler Alert!I thought the spotlights were a nice touch, but not all that difficult. Now Luigi's 100 coins thing in the Toy galaxy, it was daunting before I realised that there was more than 100 on the level. Once you understand that, you begin to work out the ideal paths to take so that you don't "burn your bridges".