From what I've seen ingame and here we seem to have a fairly even split between people wanting to go full green dps and people wanting pure healers.
The problem is that I don't think the latter knows what they're asking for. Pure healing is demanding, even if by "pure" we're only talking about 50-60% healing uptime instead of the more extreme 70-80% some games had. If someone is really good at keeping uptime they spent half their active time healing but that's most likely a veteran player that knows the ins and outs of their class. For someone playing at a more average level that means they already spend the majority of their active time healing and any sort of emergency or mishap will likely result in falling behind in healing which tends to be difficult to recover from.
And with the amount of healers that are overwhelmed and panic the moment something unexpected happens, DF would be a wipefest.
Even ignoring that pretty much the entire combat system would need an overhaul for this to work, SE has made it very clear that they place huge emphasis on accessebility. And turning healers into pure healers that spend at least half their time healing after being coddled for years isn't something they'll do.
That ship had sailed years ago.
The current design can only support green dps, wether people like it or not.