Ha I do the opposite. When traveling alone I'll take whatever including the risk of a middle...but traveling with the family then 95% of the time I will pay the fees to reserve. Only a couple times was I willing to risk getting separated, and those were on flights I expected to have plenty of empty seats and thankfully it worked out each time.

This is often discussed in travel articles/blogs. The airlines have no obligation to seat you together, which they usually very clearly explain in the booking process. If this is a necessity, you should pay to ensure this or be prepared to be at the mercy of strangers.