It wouldn't be surprising. Aside from potentially hindering Bitcoin adaption, privacy feature usually leads to higher TX size or longer verification time. In addition, gmaxwell propose Confidental Transaction back on 2015[1], but it was never added into Bitcoin protocol and added into Monero protocol (as part of RingCT) on 2017.
Monero is cool and has better privacy, but we need something that is easier to implement in Bitcoin protocol, maybe privacy sidechain would work great for this, without increasing TX size.
I'm definitely not skilled enough to be called a 'developer', but I think you're just totally underestimating how difficult it is to achieve this without potentially fucking up the entire protocol. Bitcoin is already gigantic enough that we can't afford to move fast and try to just push upgrades under the sun.
No.
Real problem is that certain someone doesn't want to have any privacy on bitcoin, and on anything else that people use for that matter.
There are other coins that have much better privacy, so it's possible to do it and we don't need a century to do that.