The more honest and even more cynical side of me says that vendors are under more pressure to deliver buzzword compliant products than they are good ones, because PHBs are better at recognizing buzzwords than quality. Therefore SOAP is better than CORBA because it is a newer buzzword, and also allows them to use the XML buzzword along with all of the attendant marketing-speak.

I am curious why it is (in your opinion) that the major players want to replace CORBA with SOAP, when the latter seems less scaleable?

One reason is that SOAP is scalable enough for many people. With organisations introducing web infrastructure for other reasons supporting two mechanisms (or, if they've never had CORBA in the first place, introducing a new one) can be a waste.