As a player with a larger airline in several game worlds, I disagree. Having competition makes things more interesting. Even when I haven't been the biggest airline even in my hub, it was definitely more interesting to have that competition than to have a half empty world where it is easy to make money and nothing interesting ever happens.
As for the 737, I wasn't around my computer so I am completely shut out of the 737 as well, so what I do have to do? Change my strategy and pick less popular airplanes. This is something that all but the top handful of airlines face at one point or another. Now I'm leasing 707s even though they are not ideal because WHY? because they are available in quantities, even though I am looking forward to the day that I can retire them. Same is true with smaller aircraft. There are always options available, it's a question of whether or not you can be satisfied and figure out how to make an airplane that's not ideal work.
I agree with LemonButt that perhaps some change in approach may improve the scheduling aspect - i think the 6 month spread idea is not practical. Why order a plane and deal with commonality costs if you have to wait 6 months to get just one more. I think a better idea to promote equity in the initial launch would be to have it be a dutch auction type approach. Airlines that want to be guaranteed a huge order would have to pay a significant premium to an airline that is only looking for 5-7 planes or take a risk that they would have significant delivery delays.
Additionally, the number of monthly production slots would be a function of the initial interest shown in the auction based on # of airlines submitting a bid, rather than the number of aircraft ordered. also the frequency in which an airline can get a slot would not be increased as the number of production slots increase, so that the increase in slots would benefit a wider number of airlines.
i know this isn't exactly realistic, but may improve game play.