The surveys do seem to vary in quantity and quality (amount of E$/time).

Funny, but they always seem to know when I am on vacation and have no access or desire to access a computer and then they load up the inbox with surveys.

The biggest advantages though, are times like now, with the current Delta 5 partner/5K promo. Cashing in 25e$ gets you 500 miles plus the 1 of 5 needed credits. Now if you were P.O.'d about something erewards was or wasn't doing to you and missed a 5k bonus by one partner activity because you cancelled and closed your account, wouldn't that blow, at least a little?

The value of the rewards themselves, though limited per year and in total seems to me to offer its highest value in simply offering a partner activity at no cash cost in multiple programs (AA, CO, NW, US, DL).

Even if you never flew, or never even wanted to do a bazillion surveys, you could keep your accounts active in from one to all of those programs for $25ereward to $125ereward. That flexibility in and of itself is worth many of the inconveniences and inconsistencies of the program.