The purpose is to have fun while playing it. It's more of a silly little romp with stuff mishmashed in/heroes from different games/old enemy remixes than anything "Serious" or "insightful." The question is whether the gameplay is fun, but that's pretty specific to the individual playing or not. A game can have all-new graphics and crap gameplay (Judgement!), or it can have a ton of recycled stuff and awesome gameplay (Symphony of the Night, which arguably got this whole recycling thing started)
Or Castlevania III, which recycled a good amount of CV1 stuff, too. Diod some good graphical upgrades in the meantime, but there was plenty of copypaste back then.