1. Experience, experience, experience! This is one of the biggest reasons. I know many of the side quests, especially in the beginning worlds, don't seem like they offer much in the way of experience. However, every little bit helps push that experience bar to the next level. Being a higher level will allow you to learn new talents and powers, get better gear, train up companions to a higher level and get a better ship! As you progress through the game, especially once you get to Mooshu and higher worlds, you will be glad for all of these improvements to your stats, trust me!
2. Nautical Experience - While a new ship is always awesome, outfitting it with higher level gear will make you almost unstoppable! Ships may have a level requirement, but all the ship equipment requires you to be at a specific nautical level to use it. And other than fighting ships, doing all those side quests is a great way to gain nautical experience.
3. Show me the money! Or.....Erm......Show your pirate the money! So many (maybe all) side quests give you gold. And pirates need A LOT of gold! From gear and ships to training up companions and pets, this game has so many features that require in game currency. Not only will you get gold as a reward for side quests, but you also get gold for defeating the enemies. Double bonus!
4. Companion Training Points - Training up companions to their max level can take a lot of time and gold. So why not speed the process up by getting more training points from side quests? I am actually doing this now with my privateer.....Doing quests to get tomes so I can max out companions and set them to getting me even more tomes to max out even more companions. See how that works? :D
5. Expand your crew - And I don't mean just companions, although you can earn many companions from side quests. You can earn pets, as drops and as quest rewards, as well as unlocking companions in the crowns shop. You can even unlock the Pegasus mount by completing certain quests in Aquila!
6. Practice Points - This is mainly for the Prospector Zeke quests. By doing these quests (one for each world) you can earn practice points, which you can then trade in for new powers and talents. Powers and talents, might I add, that you wouldn't normally be able to train on your pirate. These are especially helpful for the new Mysterious Trainers that were just added in game.
7. Badges - Some people *cough* me *cough* like to collect the badges in game. If you're one of them, doing the side quests is a must. You can earn sooooo many badges for defeating bosses, completing quests, visiting certain areas, etc. You can even earn badges for completing every side quest in each book!
9. The stories - In my opinion, this is one of the main reasons to do the side quests. The game's writers have really put a lot of thought and time into the whole game, including the side stories. Some of my favorites are in Marleybone. There are pop culture references galore in many of the quests. Why would you want to miss out on that?
Some of you may argue with a few of my points, saying that companion tasks allow you to gain NXP, gold, and training tomes. I will agree! That is a great way to get those things and I use them as well. However, doing side quests speeds things along. And it brings me to my last, and MOST important item on this list:
10. You get to play more Pirate101! And who wouldn't want to do that? I often hear people say that there is "nothing to do" in game. Well, it makes me wonder......have they all finished every single side quest in the game? I know some have, but I doubt everyone has. If you want to play Pirate101, log on and tackle some side quests. More swashing and voodooing and blowing stuff up! How could you not want to do that? And if you have done all of them, you can always grab a friend or three and do some farming!
Anyway, that's my list. As you can tell, I am a big fan of side quests. They really do add a lot to the game and I think everyone should take advantage of their many rewards. Good luck and thanks for reading! :)