This stuff comes up every few months.
I hope you really know what you're doing. TF2Lobby is the largest recognizable pug system TF2 has ever had. It's simple design and ease attracts new players and welcomes old ones. It provides a entry level system for users who consider IRC too difficult and two-folds as a 'filter' for more skilled pug systems.
There are only two honest flaws that I see with TF2Lobby (aside from a few minor tweaks, some have been mentioned in above posts):
1. skill-categorized pugs are not supported by TF2lobby automatically. However, I would argue tf2mix and tf2.pug.na cover is. Unless you plan to attract the entire competitive community from pub to invite... this is a non-issue.
2. a functioning karma system is a mild issue. Having a fully automated system would be welcomed by most but this would be difficult to implement fairly.
But as always, any time spent on advancing competitive TF2 as a developer/mapper/caster/mentor/etc is appreciated by everyone! So thank you and good look!
I'd love to chat with you more =)