Well for me it's a bit of both really. I can see how it's a good thing and a bad thing.
For me, It was required that I attended school in both primary and secondary school, which I did to a rough average of 98% and I had a load of friends and we all had fun but due to the teachers that we all had, none of us were very smart. Our English teacher was a drunk and throughout secondary school our entire English class failed our GCSE's. We had 3 Maths teachers, one of which was Polish and was unable to speak a single work of English, simply had a masters in Maths which resulted in most of the class failing Maths. Our Drama teacher was a known drug taker and was high during most of her lessons which, as you guessed, resulted in a large number of us not knowing what we should do and failed our GCSE's.
Now, this was all done before I had access to the internet, online courses, youtube or websites dedicated to educational information.
Ever since my high school days I'm in University now and have been through college and uni for 5 years. Through those 5 years I've self taught myself Maths, English language and literature, Welsh and how to use computers and have corrected all the wrong and useless information that I was told or was taught in High school with the use of the internet and online courses. Hell, even a party trick of mine is to tell you a cube root of a double digit in a matter of seconds! In school that was an impossibility.
The worse part of all of the above is that I don't live in a run down place that no one cares about, it has respectable reputation that most people have houses, jobs and are middle class. It's just a poor school and is the only one around here.
With all of that being said, we move onto college. During college I was doing a national diploma in computing, which was us required to be in 5 days a week, to which I also did to a 98% attendance and things went great. Out website teacher didn't know HTML, our animation teacher didn't know what flash was (which is what we were required to use), our Welsh BAC tutor was never there for class and our graphic design tutor showed up for class once in every 3 months due to health issues (Not saying he should of been there, just that these circumstances occur and we have no replacements for them). I managed to pass the entire course with the highest grade possible, how? I used online courses and videos to teach me what I needed to know.
I'm not saying that online courses and videos should replace school or anything, I'm simply saying that used next to them they are very helpful. I'm sure everyone gets useless teachers and some teachers have something come up so that they can't help or can't attend their classes so to use something like YouTube or Lynda.com it makes it less damaging and gives you the ability to get that grade everyone deserves and tries to get.
As far as your point of it removing extra curricular activities and such... In primary school, secondary school and college we had none. Other than the football team (Not American football), Rugby and basketball of course. There was no film groups, reading groups, drama groups, woodwork 101, engineering 101 or even groups to meet new students and hang around after school. None of the teachers or lecturers wanted to give that time to supervise them in any way, so we just never had them.
Outside of school there wasn't that much to do either but most of the things around here start at roughly 6 and on so it's not a real issue for having to look into online resources for a lesson and then go to a club or something.