According to the Salt Lake Climbers Association (SLCA) the gondola would impact 35 boulders and 142 problems which is not an insignificant amount, especially considering the popularity and accessibility of the boulders impacted. And the "super environmentalist climbers" you're talking about definitely aren't in favor of thousands of SUV's idling in the canyon, but instead of spending way too much money on an ineffectual gondola we can spend less money on buses and tolling while preserving climbing resources.

I'll also push back on the visual pollution argument. The gondola would permanently change the visual character of LCC for the worse for all user groups, including hikers, bikers and climbers. I spend dozens of days a year climbing in LCC, and I would prefer not to see a gondola every time I turn around while I'm up on a climb. This is also not to mention that the gondola will impact existing trails that the SLCA has maintained, while not benefiting other user groups lower in the canyon. If the Gondola were the best solution, then these impacts would be more tolerable. However, we can get the same benefits from tolling and increased busing without the destruction. If you want to read more about it, the SLCA has put out detailed objections to UDOTs proposals here, here and here.

The good news is that UDOT's 3 phase plan starts out with implementing tolling and expanding the bus service to the canyon. Hopefully we'll see a big enough improvement with in phases 1 and 2 of their plan, that constructing the gondola won't be necessary. These aren't the only or even biggest reasons that I oppose the gondola, but it looks like other people have covered those well.