Power creep for a cooperative game like D&D is obviously different from power creep in competitive games like Magic the Gathering (where, incidentally, WotC also has a bad track record with power creep in the recent years...), but I still think it should be avoided. This for a simple reason: I like simulationist or narrativist games, where the main aim is either having an immersive experience where the players feel like a specific character and get to enjoy the consequences of playing that specific theme (careful abjuror, hopeful cleric of light, etc.), or the aim is seeing how the story develops at the table starting from the narrative premises. In other words, I'd like my players to choose a specific class or race in our game of make believe because they like the flavour, either because it's the kind of persona they want to immerse themselves into, or because they like the narrative potential of these choices. This isn't to say I never play with gamists who like the challenge aspect, but I'll freely admit that I always find it difficult to cater to their tastes.
What power creep does (when it doesn't also retroactively make older choices better, which was my choice in the poll) is that it makes some choices better on gamist grounds, which could lead to the players choosing their characters for reasons that don't gel with the experience I'm trying to curate at my table. Perhaps you'd like to play the Cleric of a Light deity, but why do that when Twilight Cleric is stronger to the point of trivialising some encounters? Perhaps you wanted to play a Draconic Sorcerer, but why choose that when Clockwork Soul expands your spell selection so that you're no longer limited to 2-3 tricks like the older archetypes? The problem isn't necessarily that power creep adds new things to the game - the game would get stale if we only had the selection from 2015 - but when new choices supersede old ones and the old ones had nice fluff that is then missed out on, it annoys me. This is why I either try to bring powercrept options down to the earlier options (what I did for Twilight and Peace Clerics), or bring the older selection on par with the new content so that those can still be chosen (which I did by giving all old Sorcerer archetypes origin spells and making Tasha's optional class features automatic instead of optional for all classes).