I've rented a road bike in Australia; decent Merida something or another, was pretty much brand new and nice to have a "different" bike than my usual; did take my saddle and pedals, so comfort was OK. Also rented in the Cook Islands, meh experience; mainly as the road is pretty rough anyway; would have been better served with a cross or gravel bike than a road bike (did see a couple of local tri-guys on TT bikes....must have serious pain thresholds). I'm a lot more tempted to take my own bike next time than rent.
I've got some friends that do one or two bike tours a year and they ALWAYS rent bikes. They figure that they'd rather not have a problem (bike didn't arrive on time, or is damaged; also... no bike bags to deal with).
So, two different ways to look at it I guess.