LogFAQs > #928719684

When it comes to anything regarding Turkey's cozy relationship w/ the US, the answer to "why?" is the same reason that region has been fought over and important for centuries if not millennia:

Location, location, location

Present day Turkey is located in an extremely strategically important spot between Asia and Europe. For most of the area's history it was important for land crossings and the shipping lanes it provided. More recently with the advent of missiles and aircraft it is also an ideal base of operations to engage targets across the Middle East and Russia (or if they were Russian allies, swap the latter for Europe).

They're an ally of convenience. Just like Saudi Arabia (oil). Nothing more.
The regime in Turkey currently is abominable and we absolutely shouldn't be allied with them, but we can't afford to sour relations with them. I'd argue even more so than Saudi Arabia.
It sucks, but short of trying regime change or conquest...not much we can do about it.