Lol. Most 4.0 players could underarm the serve in and be competitive at that level. Very few 4.0 returners will "aggressively take control of the point." More likely than not, your average 4.0 who tries this will overhit the return and give the server a free point.You cannot have a slow serve, or even 4.0 returners will aggressively take control of the point. However, emphasizing speed is only good up to a certain point. After achieving moderate pace (enough to make sure the returner can't step in and pound it), trying to achieve extreme pace for the rec player is a fools errand.
Overall though, the serve is under emphasized and under practiced at the rec level. In most (maybe all?) rec level matches, holding serve is meaningless. IOW, players are equally likely to win return games as they are service games. Even some stand a better chance of winning the game if they are not serving. Instead of the match being "on serve" they are "on break".
Getting the ball in play is underrated, specially among middling recreational players. That's why pushing wins