In my experience, reading a DVD at ~10MB/sec is a reasonable expectation, anything more than that is fortunate. 10MB/sec is well within USB2's limitation (~25-35MB/sec depending on the controller).
Writing a DVD: DVD writers top out at 16x which is meant to be something like ~22MB/sec, but I don't think I've ever seen a drive actually achieve it, it's like when a SATA SSD benchmarks at 550MB/sec but the best I've seen in real-world copies is about 350MB/sec.
Maybe reading a DVD for imaging purposes (ie. instructing the drive to sequentially read everything on the disc regardless of file structure) may result in higher throughput, but aside from ripping DVD movies, I rarely do anything like this.
The only other thing I wonder is whether bus latency of USB3 might result in overall better performance despite the peak throughput not being noticeably better.
Overall I'd say if getting a USB3 enclosure wasn't much different in cost I'd go for it because it provides more long-term flexibility, such as connecting a BR drive, SSD or HDD.
Unless the enclosure is faulty I doubt there's any kind of reliability argument to be made. A decent USB cable is more important for USB3 in my experience, but that's a reliability of transferring data argument rather than longevity.
Longevity: In my work I've gone through a few USB HDD enclosures, they just eventually fail (although my current one has done a lot better than predecessors). My guess is that my use of them involves connecting up different drives on a regular ish basis whereas I imagine most users just have one drive and it stays in the enclosure so less wiggle stress (technical term) on the enclosure's components.
The only thing I'm not 100% sure about is whether one can simply connect up a SATA DVD drive to a generic HDD enclosure or whether the enclosure's electronics are expecting a storage device that can be presented as typical USB mass storage.