It’s not just the animation. It’s the aestethics of the mid-90’s anime, when animators found a fine edge between quality and quantity of work, but still didn’t use the computers and CGs to simplify things. Because of many factors, most studios (and by extent, most groups of animators) had their own very distinct style, much like renown mangakas, and that was for the most part washed away in the early-mid 2000's when aid of CG made more than half the anime to have same unified look and aestethics.

For me, the whole OVA series reek of mid 90-s feel, and I adore it for that, because that’s my favourite period in animation.