A good example of a character who's PL combo damage is consistently higher than a PB would be Mila. She has the easiest PL combos to pull off and can net a lot more damage than most of the cast is capable of dealing. How?
In a non ceiling hit space she can immediately perform a second fully charged PL (so the command is


:[[p+k]]: >


:[[p+k]]

and juggle for weight class into either a knock away juggle finish (usually either





or





) or a

into Mount throw finishers (which is optimal in open space). After a CB (calculated for a stun hit so add 20 for raw hit) she can deal between 77 and 127 damage on Normal Hit without wall hits or Danger Zones. In the case you are broken out of Mount you will end up only doing 77 damage. 3 Damage below a normal Power Blow is pretty good (yes you could argue it is still less than a PB but you sacrifice 3 points of damage to attempt to get an extra 47).
In a ceiling space she can net up to 114 damage in stun/CB (again with the risk of a Combo Throw situation) but attempting to net over 80 damage otherwise with her strikes is extremely difficult in a CB launch. With a raw PL in ceilings she can get a guaranteed CB (again, with a RAW PL) and net even more damage (up to 176 total damage without breakables/walls/DZs on normal hit).
With characters who are able to ground throw (unless Bass is going for a Pickup game) their optimal finishes are to attempt to get the ground throw by any means necessary, if they have an air throw go for the air throw unless there is a combo that exceeds that of the air throw (only characters I can think of that this applies to are Hayabusa and La Mariposa). Because throw damage isn't reduced or increased in juggles they tend to have the higher damaging combos at the risk of being broken.
PL and PB use is circumstantial. If I know I can get more damage than one by doing the other in the current situation then I will opt for it. In terms of game play PLs definitely do not suck, aesthetics shouldn't be the reason you don't use one of the better universal tools the game lets you have. You just have to practice all to hell to get used to timing out combos to get results.
Edit: Where did the 100-110 damage threshold stuff come from? If the PL combo deals more than 80 damage it deals more damage than a normal PB.