Rule Number 1;
"REAL FIGHT" = IF YOU LOOSE THE FIGHT YOU ARE DEAD.
Anything less than that is a playground spat or a game/sport competition.
In a "REAL FIGHT" your best opportunity to stay alive is to be mobile. To be mobile means to stay on your feet and move. If you do not understand the concept of "Shoot and Scoot" mobility may not really mean anything to you. Distance is your friend and movement with proper reconnoitering equals distance.
If you are in a position where you feel like paying some kind of movie stunt man scenario and do a non warranted diving role, forward or at any angle you are limiting your mobility due to the fact that the roll was used at the wrong time. You are dead or at the least seriously injured.
If by chance, in a combative situation, where you are forced off balance and have the fortunate happen-stance to be separated from your foe to a degree that they are unable to role with you or recover from the dynamics of their motion quicker then you can from your dive roll, then you are more likely to be able to stay alive and inflict a stopping attack on your foe.
The pre-requisite is that the dive roll has got to be a natural flowing motion from the situation at hand, not "Hay, it might be time for me to do a dive roll and magically win this confrontation".
If you do go down to the ground in any life threatening confrontation it is by far best to be back on your feet as quickly and smoothly as possible. A dive roll can be one of the transitional techniques that teach you that smooth transition.
All that being said, if your goal is not true survival based martial arts and just want to play sports games, a dive roll will probably still get you stomped if you decided to do one at an inappropriate time. Basically for the same reasons as above.
All things have their place, and time, some things have only certain situations they should be used.
Some things are for training only.
I clearly delineate this to my students.
Always institute the KISS principle in combat.
K-keep
I-it
S-simple
S-Stupid!
I would also suggest that you stay with one base martial art until you understand all that it has to offer you. Watch the senior ranks closely. How do they move, what do they do, is that what you are looking for? You will learn a lot. You can branch out, but if you have no base you have no roots or stability. You can not easily add to a theory that is ungrounded. You will be tossed to and fro.
You also have to be humble enough to learn and not know before you have been taught.