Let me start off by saying I hold a very strong opinion that new pilots should be using the "steam" gauge setup for all training, except for their private pilot, where they should be using outside references for the great percentage of the time. If you think for one second that we don't need to learn to fly by looking out the window, you are mistaken. Before I go on, I share a story...
We were departing one day in the RJ, and had run all proper checks on our instruments prior to departure. Somehow, on the takeoff roll, our heading indicators swung massively off course, so that after takeoff our heading showed 90-110 degrees off. Luckily it was a clear day, so being my leg I just flew airspeed, altitude, and standby compass, but most importantly checked these against the two greatest instruments God has provided pilots: The horizon and the ground. We quickly resolved the problem and were on our IFR way. I just can't stress the importance of looking out the window!
But I digress...
For four years of college I spent my time studying Aviation Human Factors, much of it relating to cockpit display systems. I have had it beat into my head the multitude of reasons why glass cockpit designs are safer for the modern pilot. They are much more intuitive at quick glance for the pilot to know their speed, altitude, position, and attitude. It is very easy if you look at the G1000 package: It is all aerial maps, a compass, a massive attitude indicator, and speed and altitude tapes (which are very intutive). A pilot can quickly gather and compute the information displayed in their brain, without having to interpret it like they do in older "steam" gauge setups. Isn't an altitude tape that moves down as you go up (as if you are climbing a ladder) easier to understand for height than a needle going in a circle? Yes.
Thing is though, what do we want to teach new pilots? I'd say we want to teach them to take information, some which is rather non-intuitive, and learn to construct a "picture" of the flight with that information. By giving a new pilot glass, you are creating a situation where the flight "picture" can be easy to decipher. When you put them in front of a six-pack, it is much more difficult to decipher the needles and dials (many in similar colors) to create a mental "picture." I'd rather teach a pilot to read and understand the difficult dials than just reading the information off a screen. It helps develop the pilots brain to interpret information better to understand where they are in the three-dimensional world that is flight.
I don't even need to describe the problems created for a new pilot with the GPS overlay maps and airport diagrams. How will a pilot ever navigate using a tiller in one hand and a chart in the other? I guarantee that if all future pilots in training never must learn to use a 10-9 chart (airport diagram) to taxi without a GPS map, there will be many runway incursions in the future as they move to equipment as professional pilots that do not have such luxuries. It is hard enough as an airline pilot to taxi "heads-up" with all the checklists required on the ground, now throw in no prior experience having to mentally picture your position by referencing runway signs and landmarks at night? Dangerous position.
I equate the glass and steam argument like this: Would you teach your child to write their ABCs with a pencil or type them on the computer first? Steam gauges are the "pencil" of a pilot, where you must create a mental picture and use the tools in hand to accomplish the task. Glass cockpits are the "computer" of a pilot, where the letters are in front of you, and you just need to pick the right ones to spell the word.