One common thing we all face (as guilds) and every gaming company faces is that there is always a certain percentage of people who will not be satisfied with something. PVP is always a hot topic and there are so many variables that having two server types only makes sense, especially when your talking about a game that will attract a high number of subs.
Comparing Darkfall and Mortal Online is not a viable option because they are entirely different games solely based around PVP with horrible PVE. RIFT is the type of game that will be based more on PVE and PVP as a secondary . This does not mean PVP will be bad, it just means its not the sole focus of the game.