Is it bad to give equity to contractors?

Most of the advice I've solicited on this topic says you should never give a contractor equity. I have a contractor who is building an app for my startup (we have the backend built ourselves) and he's open to accepting half in equity for his work on the project. 

Many people have told me "don't give equity to anyone who you don't imagine working on the startup for 5 years or so" and I can understand that. But on the other hand, giving equity to a developer also means he believes in the project, will be more invested in the success of the startup, and deliver higher quality work. My reasoning for wanting to do this is that I'm short on cash. I've raised $25k angel investment for the startup so far and this development cost is $12k, so giving some equity could reduce that to $6k.

Thoughts? I'm just generally curious why people are so against this.

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Daniel Thenbaum
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