I think it is nice to have the option, but it isn't always necessarily the best fit for every situation or everyone's labor.
With my oldest, I was at a hospital with a CNM practice. You could labor but not "deliver" in the tub. I felt great as long as I was upright, walking, sitting on the birth ball, on all 4s, etc. So I just kept doing that (and listening to my Hypnobirthing CDs nonstop). I did "have" to have intermittent fetal monitoring strips done (which knowing what I know now I would have declined), and that was the only time I was uncomfy for the most part. Around transition I was having a lot of rectal pressure, etc. and the midwife and doula suggested the tub. It was *okay* but when I was ready to get out, I was ready, kwim? I got out and was pushing shortly afterward. That experience would have been awesome had my (then) med-wife not gone against my birth plan and gone into crazy mode with having nurse/DH pull back my legs and do the whole coached pushing thing, etc. But overall, I don't regret not being in the tub at the end. Even if I could have delivered in the tub, I would not have wanted to with that labor, kwim? It just wasn't what felt right.
With my 2nd, I was in a new state and at a freestanding birth center with a tub available. I showed up 10 cm dilated but wasn't pushy yet (membranes still intact, etc.) I had the option to be in the tub, but just didn't feel compelled. Ended up eventually pushing on the bed in sidelying and my midwife was great with letting me follow my own urges and I basically "breathed the baby down" and let the contractions do their thing except for two short pushes at the end. No regrets with not getting in the tub for a water birth, but it was nice to know the option was there if I wanted it.
We're planning a homebirth for baby #3 (not planning a UC, so I hope you don't mind my feedback...). Wasn't sure whether to bother w/ a pool/tub this time since my previous two I didn't really feel compelled to use the tub that much, and those were fast-ish labors (6 hours 20 mins and 3 hours). However, I figured I have NO idea what this labor will bring (could be long, baby could be posterior, etc), and it is nice to have the option since you never know what you'll want in labor. So we opted for an inflatable kiddie pool, RV hose and adapter...for $50 it will be nice to have the *option* but it wouldn't surprise me if I skip it again either, kwim? I would not have gone w/ a tub/pool setup if it was going to run me $200 though (based on my previous experiences). For $50, I was willing to spend the money to have the option just in case.
SIL and BIL just had their first baby at a freestanding birth center and expected to give birth in the water. When it came down to it, SIL felt the urge to NOT be in the water. So I think it good to have options, but to open your mind to the possibility that you may want to birth out of the water.