The periodic table is an outgrowth of how many elements there are and therefore its growth is not something that can be controlled by any perception of how fast it should grow. Its growth is governed by how many elements exist and when they are discovered, not by some notion of how fast or slow it should grow.
We as humans find something new everyday. It isn't that we are necessarily changing the make up of the table, we are adding to it as we are learning more. It is going to be great for future generations to see what earlier generations found, and they themselves get to add to is as well.
The periodic table is growing as fast as it should. Really, how fast is it supposed to grow? Is there some kind of rule or organization that dictates that elements must be created and added at a certain time? I don't think so. Elements are added when discovered. That's all we need to know.
If there are new elements being discovered, there is no reason why they shouldn't be added to the periodic table. It seems like a weird idea to suggest that scientific knowledge should somehow be restricted from the general public. The periodic table should grow in line with discoveries, I think.