The title of your question and the questions you ask in your body are different so I'll attempt to answer both.
What is the use of research table in rust?
According to the Wiki:
The Research table is a new way for players to get blueprints other than unlocking with the XP System.
From this post:
Each BP can be looked at as a single craft session. They stack and are tradable, but they do not permanently unlock items. Pressing the ‘Craft’ Option on the blueprint will initiate a crafting session of the target item, assuming you have the available resources for it.
It also states that items crafted from research have a limited amount of durability and are less likely to successfully be researched again.
Is it worth building a research table? Or is FacePunch going to remove the research table in a future update?
The post listed above also mentions that the reason researching was brought back was to provide a stop-gap solution to "please all the people who were upset with the more linear nature of the XP system." The post adds that they hope it gives them some breathing room in the mean time to allow for them (the developers) to form an action plan in regards to the XP system. It's not definite that they will remove research, but it does look like they are going to plan on making changes.
Some players will argue it is worth building, while others may not. The question is opinionated.