I have never played Europa Universalis, but I do know that a if the games are done well, a TBS cannot be played in an RTS format, and an RTS in a TBS format will be increadibly boring. The reasons why can be shown through the shear number of things that can be done in a TBS that would only make playing it in an RTS fashion rather frustrating. Say, for example you were playing Sword of the Stars in RTS format, Sword of the Stars being one of the most simplistic stratagy games I have seen, it insults the very idea of what a Space 4x TBS should be. Yet even with that said, you would need to design several different types of ships with the tech that you have, manage at least 20-30 planets, and then have combat(at times with 2-6 battles taking place at one time). Now, say we actually made this more like a TBS should be, lets say that on those planets you have to manage, there is actually buildings you can place, and locations of where to place them, then lets say you only had a certain amount of room in which to place them, futhermore, you have orbital structures, shipyards and ground units to manage, oh and dont forget about the rest of your planets and moons in that system. Well, now that you have managed all of that and it has taken say maybe 2-5min per planet in the system, you come out of management to find that 3 of your 25 star systems(A, B, & C are being attacked. Which one do you choose to defend? well lets say you pick the one that is most valuable(B your bread basket system, it has 30% of you total food output for your empire). You zoom to the battle and find a nicely sized fleet. You then coordinate your defense forces, make sure yous stations and planets are at full alertness and the like and you then begin to repel the attack.
Whew, that was close but it only took you 10min for that fight, and another 5 min for the clean up afterward to make sure your system will get rebooted. But crap, you now have to manage the other two battles. At one of them(system "C"), your AI defenders won, but you still have the manage clean up a little bit but the other, it appears that one of your HUMAN opponents(given that this is multiplyaer) thought that the battle for system "A" was worth his/her time and he/she kicked the pudding out of your forces, has made landings on several colonies in that system and has sent his/her fleet to another one of your colonies. Not only that, 15 worlds over 9 systems are complaing of food shortages since the system you defended(
was your bread basket and got jacked up by the enemy even though you repeled the attack. In addition you have 3 diplomatic envoys asking to speak with you 2 of them standard trade aggreements but the 3rd is form one of the Human players and it has text to read. Not to mention your reasearch is done, you need to construct a fleet of Ships and transports to retake system "A" and the new DN class warship wont be coming online since it was being constructed in system "A" unfortunatly, that player sent in bomber wings against your construction yards first thing.
More happy news, two other human players now see that you are occupied with the battles and whatnot so they are forming a military pact to attack your outlying colonies. They already have 2 to 3 fleets each on their way, bu you dont know that yet since your busy.
You would end up losing something like that since it is done in Real-Time and you not because you are an inept commander(although you may be) but because you simply can't manage everything at one time. That is hte reason for turns, that is the reason for the TBS games. They offer more then a RTS ever could. They are ment to be played for hours, days, weeks, and some times months just for one game. And since it is turn based, everyone is at the same place on a save, you can take as much time as you need ot catch up on the game if you play 2 weeks after you last session.
In an RTS, the reason for it being so simplistic is, that you can't possibly do what you can in a TBS.
Another way to think of it is something like this, a TBS game is like running the Empire and a RTS is like running a fire-base. The fire-base has pretty much one goal, and that is to be a fire-base. Send ou patrols and the like over and over again(bad analogy but nothing else comes to minds right now).
When I go about creating my game, I wont sit down and have a discussion with my team about weather an RTS or a TBS will better, I will simply say, "We are going ot do and RTS and a TBS, which do we do first?"
They are two different animals. Useing Civilization as an example probably was not the best of choices, but using that, a small map doesn't make the game simple enough to play in Real-Time, it just means you get to the fighting a lot sooner with less reasources.