The Romans respected the "Gods of the Place" in foreign lands and the Roman Empire fostered an inclusive and multicultural approach to religion that sparked a number of syncretic cults
Using terms like multicultural and inclusive seems like a pretty anachronistic way to describe Roman religion.
Their acceptance was often to do with the degree to which the gods of the 'other' could be mapped on to the Roman gods and the degree to which they were seen as ancient (
religio) or modern (
superstitio). This is why you see 'modern' cults like Mithras being mapped on to the ancient Mithra to 'fake' legitimacy. Adopting and integrating 'foreign' gods from among those that you had conquered (and thus were no longer a threat) is also different to being tolerant in general and is a form of assimilation rater than multiculturalism.
You are right that there wasn’t the need for the exclusivist approach of monotheisms, and so they were significantly less intolerant than monotheists, but that doesn’t make them multicultural and inclusive in the modern sense. Paganisms generally had a significantly wider 'latitude of acceptance' than montheisms, but this latitude had limits.
They persecuted various pagans, Manichaeans, Jews, Christians, astrologers, etc at times. They burned people at the stake and destroyed their places of worship and burned their religious texts.
Less intolerant, is probably more accurate than inclusive and multicultural.
You should not only worship the divine everywhere and in every way in accordance with our ancestral traditions, but also force all others to honour it. Those who attempt to distort our religion with strange rites you should hate and punish, not only for the sake of the gods … but also because such people, by bringing in new divinities, persuade many folks to adopt foreign practices, which lead to conspiracies, revolts, and factions, which are entirely unsuitable for monarch.” Dio Cassius - History of Rome