With even a superficial study of the company, its public figures, or their publications you would know that "taking VC money" or massive growth would be anathema to 37Signals. On the level of "Doctors without Borders" going into the landmine business.
37Signals has an interesting and often counter intuitive approach to a modern software business. While I don't always agree with their methods or dogma, it is fascinating to watch what they try and, more specifically, how they actually execute on their ideals. It's like a science experiment that I don't have to pay for :-)
The worse thing for everyone, customers and voyeurs, would be to take VC money and become like Atlassian.
Profitable companies take VC money all the time. In fact, I would guess that's where most VC money goes to (despite all the high profile SV startups that get press). Companies do so to grow at a faster rate.
And they will also go take VC money ... Going to be fun to watch :)