I have mixed opinions. At the end of the day Power Rangers has remained popular enough to go on for 20+ years and spawn tons of spin offs. Another movie based on the IP isn't all that surprising because a lot of people obviously like it.
That said, I can't say I agree with Bob's logic. While Power Rangers can be compared to certain things like GI Joe, He-Man, The Transformers, and other "30 minute toy commercials" that get by on pure nostalgia, you really can't do the same with comics. Yes there have been plenty of trashy comics, and plenty of trash produced under pretty much all the big names and IPs, but at the same time comics have also had a lot of talent involved with them over the years in terms of writing and art, and a lot of the big characters did the multi-generational thing, chances are if your a Gen Xer like me your parents probably know comics to some extent, and Generation Y while fans of "Power Rangers" also tend to have some interest in these characters. It was arguably during the 80s and 90s that comics started to get respect as a more serious medium due to the high quality stuff being done, being objectively good by pretty much any standard, and I think that was a big part of why comics properties started to leak into other kinds of media more and more with the budgets to handle their subject matter correctly. "Power Rangers" is at this point pretty much a single generational thing (Gen Y, with some exceptions), and I generally haven't seen anything done under that label that has lead to acknowledgement of serious talent in writing, directing, artwork/costuming or other things. Indeed the show seems to revel in being absolute garbage as part of the appeal. You just haven't had a "Watchmen" or "Sandman" or "Dark Knight Returns".
Now, before someone jumps on me here, I will also say that at it's core "Power Rangers" isn't worse than any other super hero concept, and indeed is similar to a lot of existing concepts. The idea is basically a bunch of teenagers or young adults being given super powers to battle evils threatening earth, and having to balance the pressures of being kids with the pressures of being heroes. The general issue with the show hasn't really been the premise, but the quality with which it's been done, in theory "Power Rangers" could potentially be re-done with a real budget to work on the concepts and costumes and make it look less cheezy, or course that would possibly ruin a lot of the appeal for some at the same time. This may or may not be where the current movie idea is going. That said I do not think it's likely to see the success of comic movies (though I could be wrong) due to being mono-generational, and what's more while the potential is there I don't think it can be defended the same way comic adaptions and their fans are because so far you just haven't seen anything from "Power Rangers" that has had the community pretty much looking at it and going "okay, well, we have to acknowledge the quality of this work on these levels...". Before anyone who is a serious fan goes "well this was an awesome series" or "this was a really good episode" understand that your typical person, even in geek culture, who isn't a fan to begin with isn't likely to know what your talking about. While it took time to seep in something like say "Watchmen" became acclaimed to the point where even people who didn't know comics or have an
interest in them read it and had to acknowledge it's quality as a piece of work.
Bob's central message is that geeks shouldn't be throwing stones at each other, and I can get behind that, on the other hand I think he took it too far when he brought up things like "Batman" which was around for your grandparents. He probably should have left it with the other disposable pop culture movies. It's far to say that if Transformers got 4 movies, chances are Power Rangers can pull that down too, after all they are kind of the same basic thing, ongoing, reasonably complicated mythologies attached to fairly cheap media properties intended to sell toys. Someone who was psyched about Transformers has no right to be critical of someone for being psyched over Power Rangers, but your going further afield when you say it's the same thing when it comes to things like "The Avengers" which also had people like my dad (a huge Thor fan) to tap into because it went multi-generational, and when it comes to Batman... well, that's been around even longer, and while it's had it's downs and nearly died a few things it's always survived and managed to stay out there with some degree of a fan base.