Why are democrats now so happy with the prospect of WWIII ??
This seems like a pretty extreme generalization in my opinion. I'm a registered Democrat and a third World War is the last thing I would want, primarily because I don't think it would be gangbusters for the economy like you seem to think it would be on account of the whole super-powers-with-nukes thing. War with countries too weak to put up much of a fight could be profitable for a handful of contractors, abit at great expense to everyone else. Even the perceived "threat" of war with a super power that never quite escalates to armed conflict could be profitable for some. But actual all out war with other countries with nukes would not end well for anyone.
As for Syria, I think the strikes were a mistake though I know I'm probably the sole person in the Dojo to think so. Trump did not hit the runways and they were back up and running in the span of a day. If the point was to send a message in the vein of "Kill your people with bombs, fine. But kill your people with chemicals and I'm gonna bomb you back" then I find it dubious that Assad would be dissuaded from such a message, especially when the runways were already back in use just 16 hours after the fact.
There's no way to know now, but on a personal level it seems fairly dubious to me that someone who by all accounts had the upper hand in a civil war would risk international involvement by doing something stupid with chemical weapons. A false flag attack conducted by the losing side would seem much more plausible. But with no investigation all we have is a lot of finger pointing and death. The whole situation is a quagmire with evil on all sides and I do not see any involvement from America having a good lasting impact on the region. Sometimes when you have a region with enemies on all sides it is better to let them all have at it with each other than to jump in for a piece of that yourself.
Involving ourselves in Iraq and Afghanistan has not really made us safer in my opinion. If anything, by bringing down Saddam we may have freed up Iran to fixate their energy on threatening us where as before they were distracted with Saddam. Involving ourselves in the conflicts of others has seemingly never ended in rosier outcomes, from the days of Eisenhower overthrowing the democracy of Iran and replacing it with a dictatorship to arming and training Osama Bin Laden. Or even today, many of the weapons in the hands of ISIS were made by us. I do not support the idea of arming and training all these rebel groups to fight proxy wars with our enemies because current cycle rebels more often than not become future cycle terrorists, a perpetual cycle of war making and profit.