Some people hope that the EU will cut Switzerland's access to the common market which will force it to officially accede to the European Union and have a saying in the rules and regulations it has to adopt anyway.
According to those who oppose caps, instituting caps will cause a bunch of pain anyway. If the EU want to punish the swiss, the best thing to do would be to allow that pain, which the swiss have indisputably brought upon themselves.
The whole EFTA agreement only works because Swizerland etc. are relatively small compared to the rest of the EU. If everybody had the EFTA deal and there was no EU, the whole thing would go to shambles within a few decades.