The RS2000 had been dropped due to insurance etc contributing to poor sales. The GTi came along as something a fair bit more sportily styled to add a bit of hot hatch credibility without overdoing it by boosting performance over the 1.8 Si etc but making it more visually appealing.

Obviously couldn't call it RS, It was before the ST Brand was created and there was already an Si. Not really much else you could call it really.