Jackson has already had about average productivity for many rookie WRs in the NFL. It is the hardest position to pick up at the pro level.
We all want Jackson to contribute, but he is not a running back (a quick position to transfer to the pro level). He also is in one of the most complicated offenses in the league, and on a team that doesn't highlight rookies.
The only way Jackson will see the field more is through REALLY hard work on his part. Even then, he will take a while to earn trust.
You need to develop a long term point of view. Measure his progress in seasons and not weeks, and you will feel a lot better about his development because he has reasonable stats for a rookie, and has seen action in most games so far.
This is a guy that missed training camp, on top of being a rookie, yet has still been allowed to get his feet wet in most games.
To be honest, there are a couple players on this team that I would like to see more of, not just Jackson. This offense seems to be stuck in neutral right now, with a lot of new faces trying to get on the field, and a running game which has either struggled from predictablity, or been abandoned early, as of late. We seem to have 'weapons' everywhere, but not using any of them consistently, or effectively, at the moment.