Why Gabe?
You've had die-hard fans that have supported you for years. Any time someone would come along and shit on you or Valve countless people would defend your motives and your company, fans like me. Your company and your games are a massive source of the motivation I have for being in a Computer Science major right now. My dream job is to one day work at Valve and make games alongside the best in the world. For fucks sake, I have your business card on my desk in front of me ready for the day I plan to call you about an interview. Hell, I've even read your employee handbook!
Now? I look through these comments and across the Internet and I see literally thousands of people waving red flags telling you that monetizing these mods is a bad idea. These are the same fans who've fought for Valve's reputation time and time again. Then lo and behold, you appear on the front page of Reddit and I think to myself, "Thank god, I knew it was going to be alright." But as I read through these comments and I see people telling you not to monetize mods, or to simply add a donation button for modders, you either ignore the comments, or try and convince us that monetizing these mods is somehow going to be beneficial to us in the long run.
It isn't going to be and right now, quite literally, Valve is about one step away from turning the world's most prominent video game DRM service into the Xbox-Live Marketplace, and simultaneously committing PR suicide.
If you really are here to do what you are saying, "to collect data," then the overwhelming response from your community should be plenty of evidence that monetizing mods on the workshop is a horrible idea. If you have even an ounce of integrity, and you really are here with the intention of listening to your fans, take the warning. Do not try to monetize mods on the workshop, kill it in its tracks. This is PR suicide, the reputation of both you and your company are on such a slippery slope it isn't even funny. In fact, I'm one-hundred percent certain that the big wigs of EA are praying to all kinds of gods right now that you'll make the wrong decision.
Don't do this, I still have a dream I'll work for Valve someday, even though it's quite a ways off. I'm not going to be able to bring myself to work for a company I hate.