Exchanges will come and go, that's just part of the evolution of bitcoin. As exchanges close, others will open. We've seen several stories recently of venture capitalists and entrepreneurs starting new bitcoin exchanges and there's even the guy who is creating bitcoin ATM's.
And that's fine except they're taking large quantities of peoples funds with them. If Bitcoin-24 had said "We're being shut down, please check your accounts, you should find a full refund of your deposited balances" it would not be great but it would be OK. People (fortunately, not me) have big money tied up with someone who has not seen fit to issue more than a couple of paragraphs in explanation.