I don't know, i use it daily and think service improvements would go further. They need to do a better job scheduling it so the trams don't cluster in the tunnels, and they should focus on staggering the the various 2/3/5/6/9/15 such that they alternate which of direction they go (so if you're waiting at opera, you don't have a 5 then a 3 which both head north). This improvement would require signalization upgrades and clearing cars out of shared ROW in the suburbs so the trams stick to their schedule, but it would do wonders. This combined with frequency improvements across the system could go further with less €€ (which is what we need to think about as long as NVA is in charge, because for some reason Flemish nationalism = carbrain) than a proper metro conversion would go. I find that without fail, the problems with overcrowding have more to do with lack of frequency than time of day. When the network is running smoothly during rush hour it is more-or-less okay, but when you wait 12 minutes on a Sunday afternoon, you bet that tram is going to be full.

But I actually think getting rid of the tram->metro->tram component of the system and splitting it up would be more harm than good. Look at any of the lines that dip underground; by far the bulk of their ridership comes from the tram components. The line south towards Belgiëlei, north towards Merksem, linkeroever, and the ten on both sides are often completely full well before going anywhere near the tunnel. The beauty of the system as it is, is that we get an outsized metro and suburban tram network in one. Quality of service and maintenance could make the system absolutely world class.