There's more to being polite than setting your signature to "Thanks!" In fact, it's more likely to come off as inauthentic fluff than actual politeness. Which is more polite?
If you frobulate the widgets one more time,
I'll kill you.
Thanks!
Or:
I know I'm being a pain about this, but could you
please not frobulate the widgets anymore?
Dont underestimate the importance of "inauthentic fluff" -- such is the basis of courtesy and grace. I think dropping the fluff because is seems inauthentic (whatever that means) is THE basic social interaction mistake made by programmers and other math-y people.
I'm not arguing against having manners, I'm just saying that they're not enough. You can't say something rude and then make it all better with a token "please" or "thank you".
Only made worse by the use of "TIA", which says, "Not only am I presumptuous but I can't even be bothered to express gratitude with a complete sentence."
Interesting. I type all that out afresh each time. I deliberately don't correct any typos, so that regular listeners know it's been added by hand. The personal touch, or too much artifice? I could never decide.
Politeness is so important that I've set my email "signature" to "Thanks!"
More often than not, it's appropriate to leave it in.