I use Mail on OS X and it is good enough for my purpose. Could certainly be a bit more sophisticated, but most of the time, it works. I like to have a real email client for my mails and not use a web app.
There might be dedicated search engines for emails though, if search is very important.
See, if you use search a lot and Google has the superior product for your use case, that's totally fine. But I guess most people use Gmail out of habit and not because it is truly superior to other email clients.
I'm with you here - I also find OS X's Mail plenty "good enough," including for search. And it works great for connecting to Google Mail accounts via IMAP…
There might be dedicated search engines for emails though, if search is very important.
See, if you use search a lot and Google has the superior product for your use case, that's totally fine. But I guess most people use Gmail out of habit and not because it is truly superior to other email clients.