Acrylic will warp, even if you solvent weld cross braces to it. Drilling a large number of holes in a piece of acrylic is, at best, very difficult even using a drill press. Too fast, it melts. Too slow will take forever. All the way through and 90% of the holes will chip on the underside, so you'd have to drill part way through, then flip it over and drill the rest of the way. Too close together and they will crack. Too big and you might as well not have anything there at all. As mentioned above, the "egg crate" lighting diffuser has 1/2" square holes that invite your fish to use them as target practice.
Taking out a section of glass and attaching 1/4" mesh will look way worse than a DIY screen top, at least IMHO.
I'd stick with the DIY screen top. It blends in with the plastic trim, is relatively inexpensive, and works very well.
jm.02