*update* scroll down to my response in post 9...
Past Life flags should be tied to server for each account, rather than characters themselves, with characters getting the benefit of whatever Past Life flags you have acquired when they were created/TRed.
What that means is, if I have an account on Cannith, and I TR a Ranger, I have one Ranger PL flag on Cannith for that account, and any new char I make on that server will have one Ranger PL. New chars wont start with any other benefits of TR, just the PL flag. If I TR a Paladin AFTER I create the Ranger, the Ranger wont get a Paladin PL until I TR the Ranger again.
The benefit of this is that it would let you play multiple chars on a server towards your PL goals in parallel, rather than having to play them one after another, serially. So if I wanted, for example, an Arti with a PL in Sorc, Ranger, and Druid, I could have all four chars active simultaneously - even though they'd all be 28 point builds - and be able to mix up my gameplay a little bit, rather than be forced to choose one to run up to 20 before I can play the others.
Note that this does not change the amount you're required to play in order to earn a TR, or the cost to earn the PL - you still have to play each char to 20 and TR them. And you'd still have to TR the same specific character twice to get 32 and then 36 point builds, have hard/elite unlocks, etc.
In fact, it might even make it harder since you'd conceivably be playing 4 first-lifers to 20, rather than a 2nd and then 3rd lifer, and you'd have to equip each one individually. But I'd gladly do that in order to have the flexibility to play multiple chars without "wasting" gameplay on chars that dont count towards each other.