Not anymore. It is no longer "just an encyclopedia" and yes for many things it is very close to being the "replacement for the internet". What with spam and ads cluttering the web up. I think that precisely was the reason for the uproar.
I do not belong to any of the language communities involved, and neither do I depend on those languages for my day to day work. But languages interest me, though I am not a PL person. That is why Wikipedia is an important resource for me to come in contact with these languages. Yes, the content might exist on other parts of the web, but here it has already been collected under one umbrella. The quality on average is good, the site is speedy and without distracting cruft.
So of course that is one of the first resource I will turn to, and I have often been plentifully rewarded. Google is not the internet, neither is Wikipedia. Nevertheless if I want to search for something I will go to Google and if I want to browse something I will go to Wikipedia.
So, what these deletions mean to me is someone is destroying the value that Wikipedia has for me. I am sure many people feel the same way and hence the outrage.