Too many shite, recycled and bland epsodes in seasons one and two. That's why Enterprise failed. Had they begun with the energy and direction of season 3, I think things would have been very different.
Take a look at the Abrams' movies to see that Trek can be HUGE while merrily tweaking continuity left and right. There will always be the OCD crowd who will scream and rant - that the Klingons were wrong, the insignia was wrong, the terminology was wrong, how dare it contradict the novels and technical manuals, how dare they change date X to suit their story etc etc - but the vast majority will be along for the ride if they enjoy it.