That's fine, as long as you write it down ahead of time, and no one ever talks about a "level 15 wall" or tells me this wall is made of dreamsteel so you can't climb it, or worse, looks at the DC table for level 16 characters, finds the "Medium" and then gives me a 65% chance of success on my climb check. Characters should get meaningfully better at things, and the rules of getting better should be laid out before they come up at the table, so that players can use them. Being able to climb all the things, or unlock anything that's locked, or always tumble past my foes should be part of the game, and should be an expected growth of player power, and players should be encouraged to use their abilities to overcome obstacles.
I don't want creative plans that make the DM pause, assigns a level appropriate DC to and then lets you roll for. I want creative plans that involve finding a way to use my ridiculous spider legs and climbing prowess to tackle a problem from a more climbing intensive angle.