Well let's look at the bench guys:
Mike Lamb: Can play 1B/3B. Not a good fielder but can play those positions in a pinch. Has good lefty power, although not a good enough hitter to play every day (as we have all seen)
Eric Bruntlett: Can play SS/OF/2B(probably). Super Sub, can probably play anywhere but C. Good PHer, not much power but good speed and decent OBP. Not quite good enough defender or hitter to play everyday, but excellent Super Utility type guy.
Orlando Palmeiro: Can play all OF spots. Good lefty contact hitter, verteran PHer who understands and willing accepts bench role. Good club house guy. Not much speed or power anymore but good in the clutch.
Chris Burke: 2B/SS/OF, probably could play 1B if needed. Good fielder, would be starting 2B if not for Biggio. Track record shows very good On-base skills (batting and walking), excellent speed, not alot of power.
Back-up Catcher: All defense no bat, Quintero probably better thrower and more power, Chavez has more experience and might be better working with pitcher (not sure though). Niether will dazzle, both serviceable as back-up catcher.
So as a collection they have only 1 power bat (a lefty) and several good contact guys. All positions have multiple players for depth reasons if you need to move people around. Catcher is the only position where you have only 1 back-up type, but then who really needs more?
I find it hard to see why the Astros bench isn't as good as the others on the list, except that a couple of those teams have guys who at one time were regulars. So if a long term replacement were needed, I would say all the Astros bench guys could probably do that, with the exception of OP, but most (Lamb being the exception) have not ever started on a regular basis. Burke is likely to be the best guy to fill a regular role though. The Astros do have Scott and a couple other who might be called up should injuries be an issue, but I think the bench is being addressed from a "give the starters a break" perspective in this article. Sometimes people assume that former regulars are good bench guys, but I think that is not always the case. I think people like OP make better bench guys because they understand and accept that role and are happy with it. Former starters always think they can/should still start. Sometimes that causes issues, and some guys NEED to start to bat well too.
I am used to the Astros being overlooked though so I am not concerned. I would prefer it if one of the righty bats could also be a power threat should that be needed, but overall I am happy with the bench as is. If the Astros ever go to 11 pitchers instead of 12, look for Luke Scott being the first guy put on the bench, which gives another power bat, but it is another lefty.