Akro, There has been no change to the separation standards. Previously all aircraft were equal so if Dick entered a piece of airspace first he owned it and other aircraft were moved around him. Because he's non-ADS-B he takes up a much larger volume of airspace and so do the other aircraft we're separating him from. Instead of being able to use 5 miles separation we have to use 20 or 30 or 50 miles or 10 minutes. His lack of ADS-B is shafting those around him who have it.
No-one is treated any differently - no ADS-B no play. Be they N reg bizjet or B reg airliner. All the foreign airliners we get into ML have ADS-B.
As to the weather thing. We have no way of really knowing where the weather is or what you can accept without you telling us what you need. All we get is the same weather radar pic from the BOM that you get here on-line. One aircraft will want 10 miles off track & the next one two minutes later will sail straight through. If I think weather is a consideration I'll ask if a pilot can accept a particular heading, other than that it's up to the pilot to refuse or suggest something acceptable. We simply have no way of knowing what is out there.