Unless you choose a very popular name I definitely wouldn’t expect most people to immediately say they like it. Also I don’t think having the name Leesie would get negative reactions in general. Probably a bunch of “what was that? Leesie?” [name_m]Just[/name_m] because its not common.
Anyway, the reason Id say its not getting a positive reaction is because its not popular or classic. Its nicknamey but not a very established nickname. Also the spelling doesn’t really appeal to me either for some reason. Maybe its the nickname thing since its not spelled like [name_f]Elise[/name_f] or [name_u]Lisa[/name_u]. Reminds me of fleece? Cheese?
If you love Leesie but want a more popular first name go with an established name that you can use Leesie as a nickname.