IMO, in the short term, spending bitcoin is like selling bitcoin on exchange, and may cause bitcoin price to go down.
But in the long term, spending bitcoin makes the bitcoin system more healthy as a currency, and attracts more people to accept and use bitcoin.
I agree with you on some part. I guess if the exchanges have too much Bitcoin though, the price will drop drastically. If you use Bitcoin to purchase from say overstock.com, and they sell the Bitcoin to exchange, it would be bad no? I would assume if the exchanges have 95% of the coin out there, then the price would be worth next to nothing? Thoughts?