My two cents:
Chansey is so good that you're forced to run one or more of the checks that you previously mentioned in order to apply any sort of substantial pressure to it, otherwise it takes a proverbial shit on most teams and makes it incredibly difficult to maneuvre any sort of special sweep; so I feel what you're saying contradicts your original argument...
Don't get me wrong, I love chansey as much as the next guy, but I welcome this test ban.
It allows so much freedom to be creative when teambuilding and forces mons to take on roles that they previously never had to. With chansey around it's too easy to just slap it into a team and then not have to worry about any special threats; and without chansey around you actually need to put a decent amount of thought into your team builds to cover the main threats in the tier like alakazam and typhlosion.
Additionally, a chansey-less meta forces you to adopt a more offensive and strategic playstyle in order to be successful and that, I think, is a breath of fresh air for the OU tier