Just seems splitting hairs, frankly.
In Retail, leveling is designed to be over quickly, whereas in Classic it wasn't, it was a specific design goal to take longer.
How the players interacted with it, is a different story.
I can only reiterate that it comes across that you are arguing in bad faith.
Classic in itself has less content, of course, the entire feature of Classic is that it's the original, without any additions from subsequent expansions, it's just that when you detail every piece of content that is being added, that value is extremely subjective.
First, there is the individual, which has varying interest(s).
Sure, i can sell Retail to them by saying that they have more BG's...but if they're not interested in PvP, then that value drops to 0.
Second, if that content has a generally negative reception...then what's the point?
At least in Classic one can say that there's a fanbase around its design, i somehow doubt one can fill an entire server with Warfront and Island expedition enthusiasts.
It's like comparing a general store to a store that sells only specific stuff, of course the general store will have a greater variety of goods available, but if you want something specific, you may want to check out a specific store.