When it comes to large ship combat they are a disaster. Pure and simple.
For smaller ship combat. Yes it seems silly that a single pulse laser would destroy a Missile bay firing at the Player's ship. However, if your characters are in that situation, there is going to be more coming in than a single barrage from a 50T missile bay. Traveller Starship combat is deadly enough without rendering point defense useless.
It does take a rethink on Standard Missile tactics from previous versions of Traveller. However with the number of modifiers allowed, a hit is a virtual certainly as long as you are within sensor range. Something has to stop those missiles.
A Properly run 400T Corvette (Or Corsair for that matter.) will still rip up a 200 Free or Far Trader, even if they find a way to power both turrets with lasers. A Standard SubMerchant or SubLiner won't fair much better against either of those ships. There isn't enough power output to load up with laser turrets. A Squadron of 10-12 10-15 ton light fighters will overwhelm most Player ships in a single pass. (Hell most player ships would have trouble with 4-6 fighters.) Remember a hit that causes even one point of damage rolls on the special damage table. Those 10-12 fighters firing 10-12 missiles at a ship, under 1000Tons will pretty much gut it in one volley. Now against capital ships, especially captial ships with real armor, you need thousands of fighters. But for typical player ships, missiles are deadly. Further the lasers you have designated as point defense are firing at missiles, so they aren't firing at the guy firing them at you.
The rules may seem out of line but they actually work. (As long as you stay out of the Capital Ship range, at that point all bets are off and the system as is is seriously broken.)
The only time a ship, normally, goes down to SI damage is Meson fire. And if your characters are receiving Meson fire it is over even if they are in a Battleship.