That was the reason i bought back when it wasn't F2P. Anxious when not playing, as i was paying and not using it. Once i went lifetime, it's just play when you want, and no biggie ifyou take off for a week or two.
But it's F2P now, and if you ever subscribed, you basically have all the goodies already anyway minus the 500 Zen/month, so not sure why you'd pay $200+ more. Why not just 'mentally' spend the money, and buy something you want now and then out of that pool? You'd have to get a LOT of benefits to validate buying the LTS now, probably more straight-forward to just buy some of the Zen when you need it and can't farm DIL for it. You'll likely come out ahead.
Putting that kind of money into it also gambles that the game is going to be around and supported for quite a while longer. Not to say it isn't, but wasn't the break-even point close to 2 years to make the purchase make sense? It's been around for 3, and had some rough patches getting there. Feel it'll still be going strong (and worth playing) in two more?