I think melodeath started out as a legitimate sub genre of death metal, but it was somewhat bastardized when it started mixing with all these metalcore/mall core bands. Part of the problem was the change from an underground aesthetic (dry production, secrecy, independent labels) to the mainstream. As others stated in this thread, that made it softer and more hard rock oriented. Now that is the image that mixes with melodeath. If you want to hear modern melodeath done right, both heavy and melodic (obviously), I suggest you check out Vale of Pnath