I completely understand that being that I'm a fledgeling developer myself. However, when you're adding to an existing series with an established fan base you do owe something to those fans. My point thought is that they could take the basic plot and make it their own without necessarily clashing with what came before. The devil is in the details, as they say. MS steam made an effort with the throwback names, but too often the characters were so different as to alienate the older fans. Unfortunately this comes off to many as being a half-assed afterthought. And besides that, if you really want to do your own thing that badly as a developer, you can simply start a new IP.
Ignoring how difficult it is to start a new IP for a moment, what if MercurySteam didn't want to do their own thing? What if they wanted to create a Castlevania game, with the Dracula and the Belmonts and the whips, but they didn't want to tell the story the way it had been previously been told? The game stands out when compared to IGA's tradition, but I could easily imagine an alternate history where IGA never existed and Castlevania naturally evolved into LoS from the earlier titles, probably sans Rondo.
But say LoS had come out with no Castlevania name, change every name and mention to Castlevania to something else, people would be crying "Castlevania Ripoff!" because the game MercurySteam wanted to make was so similar even if it did offend some traditionalist sentiments. Heck, people were calling it as a Castlevania game before it was confirmed as one, and then everyone's jimmies got rustled when it actually was one.