That's not true. We have a lot of generalist bees (and other pollinators too! bees aren't the only ones that pollinate!) that can pollinate the Eurasian crops. This is also true for any other crop on any other continent. And I am dubious as to your claim about major crops. Soybeans, for example, are self-pollinating, so it would seem any generalist bee can pollinate soybean crops for better yields.

This is an issue of biodiversity. If we rely on a mono-species for pollination and that mono-species goes extinct or its population plummets, then our crop yields are down 20% until we can build up other bee populations.

This is about giving back to Nature so that She may continue to cradle us. And She does tend to punish us for "optimizing" toward one specific species.

We do enough already taking crops from one part of the world and putting them elsewhere. In exchange for that, we really ought to be trying to support the native wildlife as much as possible. The Europeans can have their honey, and I will have my maple syrup. On occasion, of course, so as not to upset Nature.