While I do get that feel with PostScript, as far as I can tell it was accidental rather than a conscious design decision.
The stack-oriented nature of PostScript appears to have been influenced by the engineers' experiences with working with some stack-oriented architectures from Burroughs [1], rather than from Forth. Some aspects of PostScript were influenced heavily by other languages in use at Xerox PARC during the Interpress era [ibid], most notably Cedar, but considering that Interlisp was also in use at the time, it's not unreasonable to conjecture that it had some influence; however, any such Lisp influence was likely subconscious, and none of the people working on Interpress or PostScript or their forebears seems to explicated such an influence (as far as I can find).
Charles Geschke and John Warnock, the co-founders of Adobe, both deny any influence from Forth, suspecting that some overlap of design requirements between the two languages led to the shared properties [2]. I know that can be hard to believe, given the striking similarity of the two languages, but it's not the only time that concatenative programming would have been independently invented: Manfred von Thun's Joy language is likewise similar to Forth, but, again, not inspired by it. Whereas the similarity of PostScript to Forth can be explained by a simultaneous need for portability and dynamism in tightly-constrained environments, Joy's similarity to Forth is a result of a desire for algebraic manipulation of program text (Forth's (somewhat) having this property may have been a conscious design decision, but I'd bet cold, hard cash that it was a happy accident).
Indeed, any of these stack-oriented concatenative languages are computationally equivalent to a transformation monoid (algebra of functions and function composition) where evaluation proceeds according to a (possibly effectful) term-rewriting relation. Viewed in this light, the stack effectively becomes a mere implementation detail as far as the semantics are concerned, but I think that any language designer starting with such a monoid+rewriting semantics, when facing reasonable implementation on real hardware, is likely to come up with something quite similar to Forth &c. That is to say, starting with a low-level focus on efficient and portable implementation, or starting with a high-level focus on code representation as algebraic terms, there's a good chance you'll wind up with something similar to an established concatenative language, whether you mean to or not.
