(Flame suit on)Why are people bent out of shape by having options? It's like being angry that SQ has 60 movies in their Y IFE. You have the option of not paying and leaving your PC off. Also, it's a bit disingenuous to have a company pay for your travel, let you accrue the miles, but you refuse to be productive (esp. if company will reimburse the wi-fi charges and you're travelling in international time zones). (Flame suit off)
Of course Wi-Fi would be extremely valuable, above any seat enhancements, food enhancements, etc. This would immediately pull business travel (esp. international biz travel) to UA if they move first v. the other US-based airlines. The costs mentioned are reasonable and I'd wager would be snapped up by over 90% of business travelers.
Laptops are difficult to use in Y however, even Y+ can be tight. Also, power would need to be installed at seats on at least a 2/3 ratio. I also agree with the suggestion this is rolled out on Int'l and p.s. service first.
For my family travel i wouldn't be allowed to turn it on however.