Ummm, that's all part of ventilation. If you don't have intake vents to allow cool air in, and exhaust vents to allow heated air out, you have no ventilation. No ventilation equals heat build up. Never good. So of course you need ventilation.
And for the record, pressure comes from restricted air "flow" - either more cool air is trying to get in than can get out (positive pressure), or more heated air is trying to get out than can be replaced by cool air coming in (a vacuum or negative pressure). Too much of either is no good and negative is rarely ever desired.
If you can only have flow "or" pressure, flow is better than pressure.
Ideally, reasonably "balanced" air pressure is really the goal. That is, a "little" positive pressure is good IF you have air filters behind your intake fans. Thus you want a little (and a little goes a long way) more intake coming through your filters than total exhaust.That helps prevent dusty air from being drawn in through other cracks and openings in the case. Too much intake, however, causes too much positive pressure and that restricts the flow and causes heat to build up because the heated air cannot get out fast enough.
Well, that is a nice looking case. I wish it had air filters because they are much easier to clean than breaking down the computer and lugging it outside.
I am a bit surprised it only supports 1 x 80mm fan in back. 80mm fans don't move much air without spinning really fast. And very high RPMs typically means loud fan noise. Hopefully it is a top quality fan. You will need to monitor your temps carefully. Hopefully, the PSU's fan will compensate.