Well, that's not the case with Westwood. The IP had a long and illustrious run under EA management, and still does with C&C Generals 2 in the works. Some people left Westwood in 1998 when EA bought the company, but the rest are now merged with EA Los Angeles (Westwood was located in LA).
I've personally never had a bad experience with EA (or UBIsoft for that matter). Origin Systems was acquired by EA in 1992, so WC3, WC4, WC Prophecy, Privateer, WC Secret Ops, WC Armada, Privateer 2 and WC Arena were all developed under EA management. However Origin screwed up Ultima IX so bad in 1999 that EA lost faith and cancelled most of their other projects. Richard Garriott left shortly after and continued to fail miserably in the video game industry, most notably with Tabula Rasa. Chris Roberts left in 1996 to pursue a career in film making.
If EA has killed off a franchise you liked you must consider that the video game industry is an industry. Mostly it's just a case of "sorry, we'd really love to, but there's just no profit in it".