It's really not that hard, it takes a bit of time to set the whole thing up for the first time, but after you are done, verifying signatures takes just a few clicks. I use Kleopatra on Windows and it's pretty simple.
Right, for later times it is faster but even with setup process, I don't think it is too complicated. I felt complicate the first time, but the second time I was familiar with it.
But verifying developer's signature doesn't guarantee a 100% security, there's always a small chance that developer has gone rogue or got hacked themselves and their keys were stolen - to cover situations like that, it's always wise to check for such problems on public media first.
Notifications or hyperlinks to newest wallet versions provides by wallets are unreliable too.
Electrum vulnerability allows arbitrary messages, phishing (theymos)I believe most of newbies instantly click on links in their wallets to visit sites and download newest versions without further investigations, and sure without wallet verifications.