Since the bass seem to like a "little" hydrilla, you might be tempted to think that it is a good thing, but there is rarely just a "little" hydrilla. When prevailing conditions favor it, it can take over in a short time. Make no mistake about it, it is a lake killing predator just like the others mentioned above! Eventually, once it has a foothold in a lake, something will have to be done, and that something will not be good for fishing!
Most of the time, these weeds are transported from one lake to the other by boats and boat trailers. You can do your part to stop the invasion by being vigillant.