The only possible reason they are trying to do this is to make the serve weaker , hence eliminate third ball attack and extend the rallies.
But again they will end up with unforeseen consequences.
They have already reduced the spin through the plastic ball . They thought it will extend the rallies, but looking at it now what has happened is two fold :
1. Lack of spin has caused inconsistent stroke making and more unforced errors. So instead of extending rallies , they don't even start at the first place. If they start then ...
2. Because of 1 , players who depend on power and by power I mean spin like Li Xiaoxia , Zhang Jike have gotten injured .
Now again , what is going to happen when the net high gets increased is either that serves are going to slow down or they are going to go long and they don't realize the full extent of the damage and any of the following could start happening :
1. Players would do more aggressive serve return and thereby ending the rally before it began.
2. People would start taking more risks on their serves to gain advantage , thereby missing more serves to start with.
3. You might start seeing more net balls , already the heavy plastic ball is climbing up the net more than the previous celluloid balls.
4. People will start doing more and more ghost serves if they are able to generate spin with the Chinese rubbers which would become un-returnable. In fact, after the plastic ball was introduced one of my 2300 level friends started doing this un returnable even with the nittaku 3+ 40+ poly ball and the game was becoming a farce and people started hating him . the only way we could get to him is if we could run along the side of the table and take the ball off the bounce and flick it with power. I am assuming that this would become even more difficult to do if the net height is increased . He was essentially making the ball go back on the second bounce with a serve having reasonable variety in placement . So we could not even predict if he was going to down the line or crosscourt to begin with ! I am pretty sure that serve will cross the increased net height making it even more dangerous
So, in summary ITTF fails to realize that this is a very delicate sport and meddling in it needs a very thorough investigation and trial period across the globe with pros and amateurs alike. Apparently, they don't have the resources to do that ,so they rush every change or make the change without enough foresight and trial statistics in hand. Also , some of the decisions become questionable when you find that Adnan Sahara's scientific advisor's wife owns a patent on plastic ball or whatever that was !!
So , it all comes back to the refrain which is, there are things that more important but much more difficult for the ITTF to do and thats why they keep shying away from the real issues, resolving which would make the sport better and more popular.
They should focus on making the sport reach more people, generate more revenue and implement the existing rules to the best of their abilities which they are not doing. Also, they should stop getting bullied by the "super powers" in the sport like China who apparently would not agree to the test that can catch boosting and make it a level playing field for the top level pros.
But isn't the story of every sport at international standard ? Take soccer, the likes of Blatter and even perhaps Platini make money from every new ball that gets introduced just before the world cup or the european championships , making them a farce and occasionally producing a Roberto Carlos freekick that gets played over and over again because its simply like Florence Griffith Joyner's drug boosted performance in women's athletics and cannot be ever emulated .
The problem is that table tennis does not generate enough revenue. So even if in other sports these guys eventually get punished because a lot more money is at stake and either the law or somebody more ambitious catch up with them , in table tennis Adan Sahara gets to create a new position for himself in the ITTF body and retire gracefully with his coffers full .
I think they should give badminton and volleyball a shot too, those are sports too and look at them with their high nets !!