I cant vouch for anyone else, but my reason is that I hate needing to "register" with anything just to get free stuff.
If I was going to pay for something I wanted/needed, then its OK to need to sign up.
But for a freebie Im going to download on the off-chance I MAY need it in the un-forseen future, I dont want to go through the
rigmarole of either potentially exposing myself to a spamming list, or waste time making up fake contact details to avoid said spammers.
Even it it is "legitimate" advertising from the site, it gets damned irritating quickly.

So unless there is something there I can actually see a use for, I tend to avoid registering.

Please note, Im not saying that Lost Climate Studios is a spammer or anything, its just one of my odd "on principal" foibles.