In this context I'm not sure what you mean by 'middle-of-the-road' player type.
Someone who has a natural/enjoyable play experience with a moderate amount of strategic decisions, as opposed to one who likes a light or heavy amount.
They meant much less. Utility spells made most of the skill list irrelevant by mid-level.
I've not found it to be so, considering:
1) the limited number of uses for spells as opposed to unlimited skill usage.
2) the tight definition of spells compared to skills, which really have broader, more open definitions
3) magic has limitations in a properly designed setting that intelligently considers the implications of the D&D rules that creates opportunities for skill users.
I've run multiple campaigns above mid level, one to the 22nd, and the rogue and the monk had plenty to do with their skills.
Craft is irrelevant when you're talking about common adventure-related tasks (barring odd corner cases).
I see a few problems with this statement. First off, I'm not sold on the pure-gamist philosophy that seems to drive 4e. If I think my character would know a craft, then I give them ranks in craft, and not worry too much about the fact that it might cost my jump a few ranks. (The one problem I do have with 3e on this score is that I think it is way too stingy with points and class skills to be used this way.)
Second, I find this to be a problem with the "set scenario" mindset of adventure design. I think it's faulty thinking to consider only a limited set of skills when entertaining solutions to a problem. Further, it's inflexible on the GMs part to not consider the tasks which a character would be good out when designing adventures. If a character is good at carpentry, someone would seek them out for a task related to that skill. (No, that does not mean that the adventure will be all about that, but conceiving how it might be useful to an adventure is usually not too difficult unless you are talking underwater basket weaving. Heck, even that suggests a mission where the players deal with merfolk traders being plagued by sahaugin...)
Finally, the player should be proactive in thinking of ways that they can leverage their unique skills in creative ways to help the group achieve success.
These techniques are really old hat for skill based games that don't fall into this "common adventure skills" mental trap. Too bad the designers didn't care to learn more from those they were imitating.