I used to visit 3 times / year. This year I will visit twice. Next year, I am not even sure if I will visit at all. I think a break from Thailand for 18 months or so would be a good thing.
The reasons for visiting less frequently are first and foremost, the high cost of a holiday there, a combination of price increases in Thailand and the strong baht. So, yes, the strong baht is a big part of it.
There is another issue for me and that is that recent holidays just have not been that much fun. Part of it is that the warmth I used to feel from the Thai people isn't there any more. It didn't matter whether it was hotel staff, shop assistants or just people in general, there was a real warmth from a lot of Thai people. These days it's not that I feel unwelcome, it's simply that the warm fuzzy feeling I used to get has gone. Combine that with the fact that a trip costs me approx. 30% more this year than it did 3 years ago (price increases and exchange rate differences) and it's just not good value for money any more, in my opinion.