A huge reason for this is arguably NIMBYism. The reason that sort of thing exists is because suburbs very intentionally separate commercial from residential, and will not reconsider as things change. As a result, you end up with putting all the stores on busy roads, and they need parking lots since the people live so far away. All of the homes go in rigidly controlled neighborhoods that are both politically and physically difficult to change. Neighborhoods used to have stores interspersed, old ones, and ones in other countries still do. They don't anymore because we cluster buildings by use in North America, and especially in suburbs.
I'm highlighting the picking and choosing aspect.
Wanna keep everything the same? Sure, argue for that, but that isn't what "character" arguments are about. It is about claiming the things that you like as inside an arbitrary sacred protection line, and the things you don't as outside. Claiming maintaining character if you don't fight every single change is a way of painting over selfish interests in the name of the community. There's nothing wrong with selfish interest, but don't try to hide behind a claim that you are doing it for the greater good, or to preserve something indefinable.
E.g. I could just as easily argue that the "character" of a neighborhood is derived from the affordability and diverse socio-economic backgrounds of residents. Therefore densification, infill, reducing parking for transit lanes and other YIMBY efforts in advancement of those characteristics of the neighborhood are about preserving 'character'.
I'll also point out that your example seems to concern public preservation of nature, not restrictions on private property. There's a stronger argument there since it is a public good. Raising a stink about your neighbor wanting to build an inlaw suite, or - god forbid - a few townhomes, or multifamily housing on their lot is a whole other thing.
If you argue that the character of a neighborhood is based on all of those things, then keeping them the same would maintain the character. What you seem to advocate is for changing them, which is then changing the character.
> Raising a stink about your neighbor wanting to build an inlaw suite, or - god forbid - a few townhomes, or multifamily housing on their lot is a whole other thing.
If someone builds an apartment complex on land near mine, the builder it is not my "neighbor". The builder is an LLC that owns the land. They do not live there and do not care if traffic gets awful, crime goes up, or quality of life of the pre-existing neighbors gets worse. That's because they aren't our neighbor. They're an LLC.
None of these are arguments from me against new development or pushing past NIMBYs where they become intractable. But if development in Pasadena can maintain as much existing green space as possible and commit to building out more, it would be a lot palatable to the "natives". And I think it would lead to better results for future residents as well. I think it's okay that people want to live in a neighborhood full of quaint small family businesses and resist the Subway and the McDonald's and the Dollar General. But that's "NIMBY" too so where do you draw the line? We live in a capitalist society after all, and the only thing preventing these large mega-corporations from being absolutely everywhere are the few NIMBY willing to say no to it with the little power they have over their slice of the world.
I'm not saying the feelings are disingenuous or that you can't object on personal grounds.
I'm saying that using 'character' as a catchall for things you personally don't like is disingenuous. It's hard to argue against since it can't be defined.
Don't like multi-story infill? fine. Argue against that specifically and provide reasons that don't rely on something indefinable. Personal feelings about specific issues are a fine reason for arguing since those can be dealt with. I can argue that parking is or isn't an issue and can be mitigated. I can't really argue that the neighborhood isn't losing its character.
I can do the same thing by invoking "problematic" which carries social connotation in the same way that "character of a neighborhood" carries social meaning. If I say an argument is "problematic" you can't really rebut in any meaningful way because you don't even know what I mean. If I say an argument is using false premises or invalid logic, there is a discussion to be had.