*Membership spots not really limited!
DC has a long history of taking characters from other companies and introducing them into their main universe. I am sure that at least part of the logic behind integrating Angela into the Marvel Universe is an attempt to recreate that on some level. Unfortunately, we're not talking about a character like Captain Marvel who at one time maintained a comic series that outsold Superman or characters like the Charlton Characters who were part of a company that was going bankrupt and were acquired a DC. We're talking about one character who was created to suit a purpose for a certain character and to exist within a certain universe. Bringing her in to another comic universe doesn't make any sense. They are going to have to completely change the character and they have already had to redesign her.
At the end of the day, they should/could have created an entirely new character. From a business standpoint, there is nothing to gain from adding this character to the Marvel Universe. This isn't a character that has a large, built-in fan base. When the final issue of Age of Ultron is released, you won't see flocks of comic fans lined up outside of comic stores waiting to buy this issue. I'm sure that the powers that be at Marvel will enjoy the idea that they are "sticking it" to Todd McFarlane but that's as far as this will go in terms of "benefits" to the company.
from a business standpoint there are gaining something from the character in the MU... Neil Gaiman is now writing for them again, which makes the whole Marvelman/Miracleman problems potentially easier to over come.