This is forum, it has to be engaging one and you should try to express yourself with two three lines or few words at least.
This is not a Facebook for God sake. :-D
There are forums who have a THANK button. Im not saying Im agree with the idea, just correcting you that LIKE is not all about Facebook thing lol.
To OP, I think having a THANK button will increase forum data consumption as far as my own forum knowledge is concerned. There are numbers of forums that I visited in the past who removed that feature to somehow minimize their loading time. I just don't know if that is another story when placed on a SMF forum.