Biggest thorn in the side of windsurfing is ..... the wind.
You need decent warm weather, safe water, and of course some wind. Pretty much 3 things that need to come together. Great, so once a week you might get the 3 things together at the same place and time. You spend 45 minutes packing all your gear.... 2 boards, 3 masts, 5 sails, 2 booms, UJ's wetsuits, harness and you're off. Get to the spot and rig up... wind dies....

.... or you get the spot and its nukin'....****, left my wave gear at home. Those that don't have oodles of super expensive gear just give up because an old 6.5m2 in 30 knots just ain't manageable.
Besides the specific weather requirements....
Windsurfing just ain't easy, its SUPER expensive, its really hard to learn, you need tons of heavy gear, a big car/trailer and it can get pretty dangerous at times.
Now take cycling..... you can go from home in a matter of minutes, it takes a while (an hour or 2) but you get a smashing workout, you can chat to your mates while you ride and the best thing is you can do it almost every day (time permitting) in almost any conditions. You don't need specific weather conditions (to a large extent). Best of all, you only really need one bike.
Its sad but what makes windsurfing so amazing is it relies so much on the elements... sun wind and water. When it all comes together however, its almost untouchable as a recreational sport.