I have been wearing belt bags for the last 8 years- when designer ones were near impossible to find... so long as you are willing to wear the belt bag after the fad of it fades, it’s worth purchasing a designer one. There is nothing like being hands free. My only gripe with belt bags is sometimes it’s not comfortable sitting down while wearing them. Also, I’d bring a larger tote for plane travel that you put the belt bag into when it goes through the X-ray machine and for putting on the floor in front of you.
I used to travel with a belt bag, and switched to a small crossbody for plane travel with a tumi packaway duffle bag that holds my purse, wrap, knitting, and snacks.