Ratskinner
Adventurer
I think a lot of people are missing what catastrophic is saying, so perhaps an analogy will help out.
I work in a shop where I regularly interact with our code developer group. The primary program they work with deals with almost all of the regulated work we do (we are a contract pharmaceutical lab).
This program was originally written in the late 90s by someone who had no formal programming experience, and they did a great job for what they knew about and what they could imagine the business would grow to include. What they did not do, and it's hardly surprising since they weren't trained as a programmer, was make things modular. At all.
Since then, we have grown to generate about 100x the work, and the software now has a team of six full time developers, who all do modular coding. The underlying code base, however, has largely not changed.
This is not good. In fact, it's about the worst thing you can possibly have, and it has resulted in the application becoming something like the Winchester Mystery House, where modules are built all over the place on top of each other. Since there's very little consistent underlying structure, it makes development a royal pain, with many, many problems, since nothing was developed to work together.
In the next couple years, we are going to be hiring a few more developers, and re-doing almost the entire thing from scratch.
Consider that redesign an edition change in D&D. If you create the foundation of the edition in a consistent, modular fashion, you can easily build out a variety of modules on it. For example, if you have a consistent class structure, you can easily add powers to it. If not, your module becomes redesigning each class from scratch.
I haven't seen much that's real about 5E, but what I have seen has not been modular at all: it's simply been a rehash of basic D&D from the late 70s. That edition is simple, but it has many, many assumptions about how classes work that are not portable or modular. If the advanced combat and the advanced powers module have to rewrite the combat and class system from the ground up, you don't have a module, you have a different game that still uses the same attributes and a D20.
I can see the point, but I feel two things make this fear a little out of proportion. Firstly, tabletop games aren't computer programs, things can be different here. Secondly, I really don't know how...given what was in the pasteup...anyone can conclude anything solid enough about the structure of this draft of a game to react this way. There simply isn't enough there to conclude that this is going on, IMO. From what others are saying about early playtest documents and experiments...its quite possible that the leakers don't even know enough about the game's (potential) structure to even give the opinion themselves.