agree about the system switch thing - if you do that to often its annoying (4e came in 2008 so thats only 3 years).
I don't mind buying supplemental books - quite the opposite - love to delve into new professions, races, skills and powers - but I stopped buying when they got out Essentials ... at first because I didn't think it was an expansion but rather the game again for new players, later cause I didn't want to confuse the rules anymore. We have actually discussed if we would have been better of just playing with the three basic books, especially considering some of the later races, professions and powers seems a little powerful compared to the initial ones