Plenty of people do care about frontend performance (as evidenced by the plethora of efforts ranging from small alt vdom libs by solo devs to large corporate efforts like AMP or m.uber.com[1])
So large library size == mediocre?
Jesus christ, HN is full of extremists.
If your problem space requires a lot of code, then off course not.
Also, library size !== mediocrity at all. No one builds an unreasonably large framework on purpose either.
And I, as a user, am left waiting several seconds waiting for pages larger than the original Doom executable to load. It's gotten so bad that my wife had to be selective of when to use her phone because browsing normally without wifi from starbucks etc would get her over the plan limit by mid-month. I mean, how much browsing are you really supposed to be able to do when every page is several MBs of JS alone, and you have a 300MB/mo plan to work with? Not every country has cheap/good mobile plans.
You do if your app needs to be mobile-friendly. 100kb can easily add an extra second or two to the page load on a bad enough mobile connection.