This is something I have recently dwelled upon, since I aspire to be a full-time climbing guide. I now see that climbing schools have had some negative effect on climbing as a whole. But the negatives are limited, and the positives are substantial. Here are some of the negative influences I have heard on climbing schools and my counter.
1) Climbing schools introduce thousands of new climbers to the sport every year making it harder to find routes without lines. The truth is climbing will continue to grow rapidly schools or not. Just like any "adventure sport", more and more people will seek an escape from their 9 to 5 office jobs.
2) Schools hog popular routes. In my experience I have seen more summer camp groups hogging crags than guided services which make an effort to disperse their profession and allow ample alternatives to recreational climbers. This is not always the case but I have heard the major schools and better guides know where to take 10 clients on a top-roping day with out monopolizing the North End or Square Ledge.
There are some serious positives out there for schools:
1) They help people who don't have a huge amount of time to "apprentice" learn the ropes at a quicker pace. They turn out safe climbers, who are less likely to ruin your climbing day by having an accident where your assistance is needed.
2) They dedicate time and energy to preserving the land, and are good role-models for Leave-No-Trace and other ethics.
3) They are almost all volunteer rescuers and will be there when it is below freezing and dark to help you out of a jam.
That's not to say there arn't exceptions. I have seen "guides" being negative role-models, acting arrogant, and even not using the safest methods available. Some are guides simply because they climb at high levels, and I wish that was a trend that would change. Good teachers make the best Guides, and get the most return customers. All inall, for those who can afford it, hiring a good qualified guide a few times a year could have substituted for the years of trial and error I went through with out better peers.
As for the bolting issues... a lot of them are very active, at the personal level, maintaining, replacing, dare I say, even chopping bolts in the valley. Since two guides in the same school may disagree on a certain route perhaps it is better that the school stays neutral.