The reason it bothers me because it sounds like an order to someone who is delivering a service for you, e.g. 'Can I have another drink? Thanks!'? That's not a 'thanks'.
and
> 'Can you implement <Feature that takes a month of work>?'
Are very differently loaded questions! The first one very much indicates no concern about the implementers time, and is very often seen coming from people that have no idea the complexity of the work involved with the "Thansk!" indicating the implementer would automatically accept it regardless of their own priority, while the second one is way more innocent and open for a reply back with "not sure if I have time for that atm".
EDIT: In short, it's a matter of etiquette, the same way nobody wants to deal with a complete fucking asshole (sorry, personal scars here...).
Something like:
> I really like NAME-OF-PROGRAM. Thanks for making it! > > One thing that would make it even better for me would be FEATURE-X. What do you think?
would be much better.
Putting some effort into the request/suggestion also helps. Eg. giving a well written rationale/use case. Saying why existing-feature-Y isn't enough, etc.
I do not understand your point of view. Should we stop saying thanks in our daily life? Because it does not really do anything for anyone....
To me the following two messages give off two totally different vibes:
'Hi, can you implement <Feature that takes a month of work>? Thanks!'
'Can you implement <Feature that takes a month of work>?'