It actually doesn't really matter if a script is big or tiny to make it successful.
For example, the MsgHelp PM Notifier is a small script which notifies you of new personal messages on these forums. I always have it turned on because I like what it does and it simply does what it's supposed to do very well.
Most of the time, you start off with a small script which can do one thing, but as you spend more time developing it, you're going to find yourself in need to add new interfaces to extend the features, expand the script functionalities and thus you'll get a "big" script, such as Screenshot Sender. Screenshot Sender started as a Plus! 3 plug-in which could take and send screenshots, but now the Plus! Live script can also save them, take screenshots of a selected area and browse through all of your screenshots. It's still a screenshot sender, but it got extended with more related, handy features. If it would still have been a simple take-and-send script, I'd still use it because it works great, but the developers felt like it was almost necessary to add more functionality, and now it became one of the best scripts around and even won the Plus! scripting contest.
Or just to keep it short: a script doesn't need to be big to be a good one, but if you feel like you can extend it with nifty features, try it. You can only gain from it, you have really nothing to lose!
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