That might have been the case in your neighbourhood, but since Starbucks became popular independent coffee shops have grown because most people would have never spent 3.00 for a cup of coffee.
http://www.businessweek.com/smallbiz/content/jul2008/sb20080718_057710_page_2.htm
Yup, chains often exist in places where independent restaurants wouldn't be able to (because their name carries cache, they have financial backing and lower overheads) meaning that they help keep dying high-streets alive, which benefits every business on that entire street and thus helps the community.
They are helpful in introducing populations to other types of food, as with bookgri's Starbucks example (the idea of buying coffee becomes a familiar and easy idea which then stretches to different places), places like "The Real Greek" are adapting and changing the way people eat and introducing them to new foods. If Taco Bell becomes a success, you may find the buzz and therefore the number of available mexican restaurants increasing.
They also employ people that are otherwise very difficult to employ (differently abled people, older people etc ) and offer training and development to their employees who in the case of QSR often have low educational levels.
During the recession chains with their guaranteed name recognition being translated into footfall are staying in business and keeping people in jobs, landlords in rent and stopping highstreets from looking like a ghost town which devalues the entire area.
They also often offer food at reasonable prices to
people who want to eat at them enabling families on a tight budget to eat out knowing that they will like and enjoy the food with little risk which is an important part of family life.
There are far worse things for communities than chain restaurants that people have little issue with (Tescos does the wonderful WalMart thing of wiping out entire highstreets of fishmongers/grocers/bakes with undercut prices which chain restaurants are not capable of doing or do not do on a widespread scale)
I probably eat at national chain restaurants maybe twice a year? But I don't hate them, I recognise their importance in the community and I'm not about to go protest a Taco Bell, I'd be MUCH more likely to protest a Tescos/sainsburys/ASDA/Morrissons megastore.
It's really difficult for restaurants to succeed in this economic environment and frankly I'm applauding any business which is contributing to the economy and keeping people in jobs.
