I don't really have much sympathy for a company that expects to reap the rewards of social media engagement, but thinks it takes way too much time to... engage socially.
I don't think you need a huge Twitter presence. It's nice to have a handle to include when I want to give feedback, but I don't follow any companies, and unless they're directly helping me solve a problem (which is rare), I mostly find it kind of annoying when they try to talk to me.
I'm no marketing guru, but I thought the whole point of social media was that word-of-mouth moves much more quickly. You shouldn't need to try to manipulate that to get attention; just build something neat enough that other people want to talk about it.