Dani,
When I look back, I started my airline training with about 400h, all of them done on SEL aircraft. I don't think that those hours really made me a better airline pilot.
The experiences & lessons learned from flying solo - even if it's in a single engine - facing real time situations such as weather closing in at destination on a cross country, or getting lost & subsequently recovering your situational awareness, or making a bad decision about something in the flight.... & recovering from it... these things cannot be quantified. While the normal 230-250 hrs is not much by any measure - it is still a far cry better than making belief in a flight simulator under the direction of an instructor who sits behind running the simulator instructor panel.
You never know how much worse a pilot you might have been if not for those "400 hrs" that you started in the airlines with.
The real training started afterwards.
Yes - and i'm willing to bet that this "real" training didn't come from flying flight simulators in lieu of the real airplane.
of strategical and operational thinking.
Compared to FOs with an extensive GA background, I don't see a big difference there. Even with thousands of hours on small planes and experience as GA flight instructors, they do generally not stand out from the ab-inito pilots. Also here, the individual quality of any candidate is much more important than its training background.
I'd say the more important issues are of a guy being competent to operate the airplane in First Officer role (SIC). That means 1) Pilot Monitoring (Pilot Not Flying) & 2) Pilot Flying in the event of a role reversal when he/she gets the leg - and being able to do it in worst case scenarios with situations of high workload & pressure. At this juncture this bread n butter stuff is the greater issue than of "strategical and operational thinking" on the company front. The order of business is
SAFETY-PAX COMFORT-ECONOMY in this sequence, not the other way around ECONOMY-PAX COMFORT-SAFETY. If he/she can't handle the airplane properly (i say "properly" not "perfectly"), the first prerequisite - SAFETY - is already not met.
Though nobody hopes it happens, if for example the Capt has a incapacitation & the chips were down with the new FO left to his/her own devices, my money is that the ones with "thousands of hours on small planes and experience as GA flight instructors" would be in a far more advantageous situation having a greater bank of experiences, purely by virtue of having been thrown in deep water before - and having survived there. I say "greater" in that 230+ hours is still way more than the 50 hours of the MPL. One learns to walk before he learns to run. By all means add sim time to the syllabus - no issue here - but not at the expense of cutting flying time in a real airplane. No sim can ever instil the kind of survival instincts that come from a real plane.
MPL proponents are trying to do just that - short cut the time into the right seat by cutting corners at the expense of the trainee pilot.