I'm not a Starwood apoligist either (being a Lifetime Marriott Plat means I've spent way too many nights in Marriotts over the years, and I'm also a Plat with Priority Club.) With that, lets look at your comments:
1. Marriott points can definitely add up and in reality, I would tend to agree that on a straight up basis, I can probably earn more free hotel nights at Marriott than with SPG. But outside of Marriott's Megabonus promos, they just don't have a lot of good bonus point promos. Take last year's SPG free weekend night promo for every 2 stays. Marriott just doesn't have anything close to that. I was able to get a bunch of free nights that were usable at upto cat 6 properties. Its these extra bonus promos that can not only level the free night playground, but maybe even give Starwood a leg up.
2. If we are comparing with Marriott, I could ask the same thing of Marriott. What is the benefit of staying those extra 25 nights (75 needed to reach Plat) beyond getting Gold? There isn't a whole lot of extra benefits that Marriott has between Gold and Plat. Both get upgrades and lounge access which tends to be the two most desired elite benefits. (Yeah, Marriott will give you some extra bonus points as a Plat and that is nice.) As for free internet access, up until just a few weeks ago, Marriott charged everyone for internet access at their FS hotels. In fact, while Marriott is now offering free i-net for Plats, it is only for US hotels. Plats STILL have to pay for i-net outside of the US. At least Starwood is now offering free i-net to Plats worldwide, not just in the US.
3. I can tell you right now, don't bring up the D word in the Marriott forum. They have a big time rep for doing the super spin-job on their devals and trying to hide things. Marriott very rarely will give advance warning on hotel category changes. And they still haven't given us a compiled list of their recent category changes even after the fact. (We had to go out and make/find our own list.)
4. Why should someone stay at a Fairfield Inn and get Plat status just the same as someone who stays at JW Marriotts? All the big hotel programs have this same issue.
5. Upgrades for both Golds and Plats suck for Marriott. Suite rooms are expressly excluded by Marriott. So if you want a suite room, SPG or Hyatt is probably your better bet. I will say that many more FS Marriotts have lounges than do Starwoods. And that is a definite plus for Marriott as far as I'm concerned. It is very nice on a trip with the family to not have to worry about paying more than $100 just to get some breakfast for everyone. ^
Basically, it boils down to this: Each program has its own strengths and weaknesses. I decide what my priorities are and based on my expected travel patterns and where/how I want to use my points, I then pick the program that best meets my needs. Marriott is a good program. SPG is a good program. Hyatt is a good program. Hilton, it is an OK program.
Look at each one and then choose the one that best suits you.