I think a basic Mage should have always been able to enjoy PvE and farming junk like any fighter archetype could. Personally I don't like Pets at all and as a mage shouldn't have to rely on one to accomplish a very basic gameplay loop. SV could have at any point in MO's lifespan at least attempted to balance the basic magery school so that it was more useful than it was. As a basic school Ecumenical is cool as something that can do a little of everything, do some healing, deny healing, some damage, it never had to be awesome for PvE, but it was the only option starting out, they should have always had at least 2 different basic spell schools to start with, jack of all trades ecumenical, but then pair that with another basic school which was only dmg focused where you make the choice that you're going to give up heal spells so you can nuke some junk and do some damage like everyone who wants to play a mage wants to be able to do, then balance around that.
Also, since Ecumenical is the utility school, put more utility spells into it like mage light so a mage can see in the dark and cast spells without having to hold a torch...imagine that....and also maybe the breathe underwater spell...it'd make that school a good choice for explorers and junk, it'd be much better.
In regards to the OP, they definitely goofed on implementing the advanced magic schools. They ruined the game with Necromancy pets, no reason to have ever made them as powerful as they were, I wasn't around to see how they ever tried to balance it, but that whole implementation was really really bad for the game.
However I do like the idea that there would be what we could consider like basic magic schools (needs to be more than 1 tho) and advanced stuff that does more cooler and involved things and is harder to master.
I also did not like, and feel it was very prohibitive to newer players looking for just like any reason at all to keep playing the game, how many hoops there was to jump through to just try out a new magic school just to see if it was even something you were interested in playing. There was such a huge barrier to entry for them that you had to invest a lot of time and money just to even see if it was a playstyle you'd like. It was so much easier if you were a fighter to play around with different builds to find what you liked, sword or maces, MA or MC, etc, but as a mage you didn't have that choice, and that problem was just multiplied for newer players, who like I was saying need every reason we can give them to see if this game is something they should stick with.
A new player would try out ecumenical and try to go do something basic and be like wtf....this is clunky, that did no damage....I'm out of mana...I cant even kill this bear...or these reagents cost me more to kill this bear when I take time and kite it around to make this at all a profitable thing to do either in time or resources. This is basic crap that was never considered...they never touched it...I just don't get it at all. We hear in all the new interviews how with UE4 its going to be so much easier for them to implement their vision and how UE3.5 or whatever was holding them back, but this basic balance stuff has nothing to do with that and could have easily been iterated on over the last 10 years...but they never even tried...why didn't they try? It makes no sense!