You Just Gave Several Good Example Of Why One Size Does Not Fit All
Your life support argument is also one that sounds good at first glance but what many people overlook in that argument is that they are giving up on technology for long term missions. Life support for a 2.5 year mission to Mars includes 1.5 years on Mars. That same technology can be used for almost a 2.5 year mission to the Moon possibly even longer. Given the closeness I'd guess few would see a need for missions longer than 6 months to a year. However, the habs could be reused by other crews using smaller vehicles. Long term missions are a key step to permanent presence on the Moon or Mars.
Regards,
Mark