why are Record companys pushing Re-Released Albums?

Mariah Carey has had a Great comeback year.but why is Her Record company pushing a Re-Release with only 2-3 new tracks within a 6 month time period?? last Year Usher's Record Label did the same thing. it's always great when a Artist sells alot of Records,but why re-package the same record with only 2-3 new songs?? it's one thing if a Record Company does something 10-20 years later on a Classic Album like Michael Jackson's Off the wall or Thriller with adding commentary,bonus material&whatnot,but just because a Album sells alot in the now doesn't mean to re-release it with only 2-3 new cuts&expect people to pay full price.that is just wrong.these Labels&some of these Artists wonder why people down-load?? use some common sense.I say if you are gonna put out another re-packaged Project then have a whole new album's worth of material.fans love Outtakes,raritys,etc..but don't manipulate the situation like this.