Because they figure if you use it that you'll want the features of their other plans...

I run the free version for every site on my VPS, it's nice; and you can mark what hosts you don't want to go through their CDN and it'll link directly (which was required to use my own domain with tumblr).

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
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