Some of us don't have swap. I've never needed it on any of my servers. If your resident set is too large for RAM, you'll have problems at the worst opportune time--under heavy load. If your virtual set is significantly larger than your resident set, then you have broken programs (probably descended from the mythical daemon which preallocates gigabytes of memory from malloc like candy, and necessitating the OOM killer). If a program wants to allocate a bunch of address space for object caching, or wants to slurp in a large data set into memory, there's mmap. Typical servers don't need swap; it's mostly brain dead desktop applications, and batch processing analytics software which copies huge datasets into malloc'd memory, and neither are heavy users of /tmp.
And I fail to see why tmpfs should be necessarily any better than a vanilla /tmp directory. Both primarily operate in RAM (tmpfs explicitly, /tmp through the buffer cache). Both spill to disk on memory pressure; probably the same disk, in fact. Instead of tmpfs, why not tweak the buffer cache? Are there any numbers comparing tmpfs with a /tmp on its own partition?