There are two sides to that answer:

1) What was wrong: the numbering of terminals wasn’t intuitive at all, did not reflect latest real estate changes (=merging 2B/D and 2A/C), and was partly totally confusing (2E-K,L and M). Therefore, yes, there was something that needed fixing.
2) Is the new concept better: opinions differ, but personally I find the re-numbering of terminals useful and more intuitive. Where they then throw away any gain in intuitiveness is by giving letters to boarding areas, which not only is not necessary but also is done in a totally random and non-sensical way. It’s a situation where the result obtained by addressing a real flaw is worse than the original situation. Some sort of “degradenhancement” (German speakers recognise “Verschlimmbesserung”)

End result: the new labelling may not be much better than the existing one.