i personally find voice acting in games like blockland incredibly out of place, (especially in something as silly as this) but that's just a personal thing
Well, it opens it up to the characters being much more expressive. Lines, read properly, can be sillier than a computer voice. I see where you're coming from, but given the pros and cons, I would still go with human voice actors.
Also, the computer voice gave the series it's own little personality
For me, that was always just temporary. I only had the three voices to work with, so it seemed I couldn't really go anywhere with it. I probably would have had to recycle one for RMS. I do admit it was a mistake to change it so abruptly within the same tennis, without any warning or explanation.
and the background noise thing the mics do annoys the forget out of me
There wasn't any additional background noise from these lines.