I've got mixed feelings about this one.
TW training CAN expose you to new techniques and require you develop new skills, but that depends on how you were originally taught, and if your experience is in the recreational/day-vfr/SEL/straight-and-level world. That said, you can pretty much count on increasing your skills.
Plus, the airplanes look better than tricycle gear airplanes when they're parked. That's the important thing.
As for needing it? For work: a 206 with biggish tires can do ALMOST anything a TW airplane can. And places where the TW is really needed over the 206 (if they exist) are places you REALLY want to think about before you go into. Not saying it's a bad idea, but be good at it first.
There are a lot of ways things can go south: like manac further up said:
Taildragger skill is highly over rated, it’s just a license to worry.
There's somthing to that.
I'm a TW instructor (the rule in the 90's requiring an endorsement created a cottage industry for guys like me). My take: You'll have fun, you'll learn a lot, and I hope you're able to fly a TW enough to lock in those new skills. For those that don't want to, that's fine too. As for the OP: if you want to further your skill development after the TW, here's what I encourage my students to do:
- Learn aerobatics, find a place you can rent an acro airplane (or buy one), and do it enough that you get proficient.
- Get an instrument rating. Fly in IMC enough that you get proficient.
- Get a glider ticket. Fly enough that you get proficient.
Each of these will teach you precision control of the airplane -- but each in it's own way. Collectively, they'll make you a MUCH better pilot. Note also that there's no TW on that list (acro airplanes - especially "legitimate" ones that have negative g capability, are almost all TW). A pilot that can do an honest slow roll will have a better understanding of adverse yaw than most TW pilots, and will pick up crosswind ops with minimal training.
A note on proficiency, based solely on my observations of students: If you actually get proficient, you can step away from each of those three for a while if you need to. If you don't get proficient and step away, then the skills will erode pretty quickly. I see a ton of pilots that got their endorsement, then didn't use it for 10 years. It's almost like starting from scratch.