Standards & pass criteria vary over the years as different elements are brought into the skill-set required of today's Commando. Years ago you had to be fit, you still do, but you have to be capable of passing technical elements of training that previously never existed. (In 1969 a computer with the capacity of a current day 5 quid calculator helped take 3 men to the moon & back- likewise warfare is a bit more high-tech.)
It has long been the claim of those who served previously that is was always harder in their day. Of course it was - have you ever heard an old duffer claim it's harder now than ever before?
When I joined the RN 27 years ago everyone claimed we recruited people that were no good, those that recruited the people that trained me were told likewise & so the myth continues.
Retention: Most people only intend serving 5 years & state just as much when they join. Surprisingly perhaps, most stay longer than the minimum 4 years 2 months, but we should hardly be surprised when they leave as intended. The current average is 6.5 years. Of those that leave to join private security firms overseas, most do a couple of tours & increasingly more & more trained marines want to rejoin the Corps.
Recruiting figures are increasing for a multitude of reasons, not least because we're entering into a recession where there are fewer securer jobs that can offer you 18 years guaranteed income or longer.
Yes, the pay could be better & now more so than ever, you will most likely serve in combat that is at a more intense tempo for a longer period than ever experienced by servicepeople ever before. In my opinion the selection process is more rigorous, with more pass/fail criteria than ever before. Easier? I don't think so.