Although I agree at-will/encounter is easier than Vancian it is certainly not the only deciding factor when it comes to newbies not playing Wizards. There is the Hit Point factor - they are squishy and since 5E is assuredly not 4E and appears to be following older schools of thought when generating hit points I still see us nudging newbies back towards melee classes.
But then there is no difference in difficulty in understanding
the game whether you have more or less hit points and/or armor.
Now as for newbies, they will not make up the majority of the market share so why all this pandering and catering to newbie players is beyond me. Their primarily goal is to unite the player base - a united player base yields an increase in newbies. Appealing to newbies but leaving the player base divided yields far poorer results.
I say go Vancian, as Remathillis said no reason to reinvent the wheel. And in the DMG or later in the PHB allow for those additional options as modules as per the OP.
Yet again, you and I and everyone here will be able to take the options we prefer without too much of a hurdle, but a new player will likely be tripping over things when they read through the spellcaster class description if it's too complex.
There is no dividing the player base when all the options that they want are given (unless they demand that their prefered way is *the* way and the *only* way - note that this simple casting is not what I would play).
It's not about reinventing the wheel. There are multiple wheels by now, and the DM can choose to pick the old stone ones, or the wooden ones, or the fancy metal ones with the rubber, if he so pleases.
If the other options are given elsewhere, who better to use them than experienced players? Let's not burden the new players with all this, so that they may actually come back a second time instead of going back to their computer games.
At the end of the day, if you're going to make it easy for someone, make it easy for the ones that actually may need it. It might be catering to new players, but you have to remember that these players are also the future of this game.