I think there are a lot of reasons, IDEA is a universal app that can't necessarily fit the workflow of every language perfectly whereas something like PHPStorm, it's pretty obviously supporting the technologies and tooling associated with a PHP app. I used WebStorm and PHPStorm for a while and finally bit the bullet and purchased IDEA because I develop in Java, PHP, Perl, Python and Node.js regularly enough that I'd prefer one IDE to rule them all. IDEA seems to prefer Java first though, whereas when I created a new project in PHPStorm it gave me prompts that would be (as you'd expect) much more relevant for a PHP app. Also, the cost is a factor- PHPStorm or WebStorm are significantly cheaper than IDEA- if I was had a primary dev stack that fit in one of the 'smaller' IDEs they provide, I'd be thankful that I was able to buy something less than the Cadillac IDE offering. Sidenote: I find IDEA to be a fantastic IDE and replaced Komodo ($200+) and Eclipse (free) with one that is much easier to use.

Along those same lines, why would a DBA want to pop for everything that IDEA supports when their primary goal is writing SQL?