One of the most useful turns of phrase in Japanese is ありがた迷惑【ありがた めいわく】, which is that of being helpful in a way that is not helpful. It can cover situations where one is being helpful to semi-deliberately cause guilt (Hi mom!), or situations where the helper is sincere but causing more harm than good.
For a long time I pronounced it as アリガタイ メイワク, because I assume it was a combination of "grateful" and "troublesome".
Since learning the correct way of saying it, I've always wondered, is there no い at the end of ありがた because it's just been dropped over time, as a set phrase? Or does ありがた originate in some other way?
So far as I've found, ありがた is not a word on its own outside of this phrase.
It's a small thing... but still... what's the deal with the missing い?
Please avoid overly technical linguistic terms and make answers readable by all. Thanks!