Wi-Fi availability has been used as a deciding factor in purchasing air fares for 66% of respondents.

Important note: these are passengers who had previously used in-flight Wifi. 

They seem to be ready to make sacrifices for that amenity alone:

Nearly one in four has paid more for a flight with Wi-Fi. One in five switched carriers because of a better internet.
A third would swap tickets to fly standby on a plane with Wi-Fi. Half would be ok to endure TSA twice. 

This is coming from Honeywell, a connectivity solution provider, so take it as you want. It all depends on who you're asking, I guess.

In Europe, those who are very price-sensitive and opt for low-cost carriers might not care at all—they'd rather just arrive in time, which is already a big win in itself.