The problem with this kind of "wait", and indeed the reason why such a "wait" tile is not offered in the Viewer already, is that it paralyzes the rest of Squeak, including the running of all other scripts, for the duration of the "wait". Thus, it's usually not acceptable within a multi-player simulation.
It is difficult to decide what to include. There are many features which are missing compared to, for example, Game Maker. This includes a bounce off other objects (except the playfield and world), variables for Cartesian components of speed and a range of triggering events for scripts. The test for inclusion should be whether it enhances etoys as a learning environment. Learning what? I would hope that the things that can be learned include vectors, Cartesian coordinates, negative number, rate, kinematics, boolean logic, problem solving.
Would a "wait" tile enhance learning? If you take a Papert Constructionist view, etoys should be a rich sandpit for building "powerful ideas" because kids need to build their own understandings in their own ways. My inclination is that a wait tile would enrich the sandpit , would allow kids to construct, in their own ways, their games and conceptual understandings. That holds true if the wait tile isn't particularly useful in most cases.
Tony Forster, Computer Game Design, Programming, Multimedia and Mathematics Cluster. http://schoolgamemaker.rupert.id.au/