While "having to" change your doctor is fairly commonplace, being able to find a new one is definitely getting harder than it was. There are more doctors retiring than are being added as new ones; and provider networks are becoming more restricted than before. There are documented stories about counties in Florida that have 19 OB-GYN total for 295,000 people, presumably half of which are women. Toss out the youngest and oldest, you still have 19 OB-GYN for, say, 100,000 women, or about 5,000 women per OB-GYN. That's 100 per week or 20 per day if each is seen only once a year. If a visit is 30 minutes long, that's a 10 hour day with no breaks of any kind to do anything else except see patients....and of course the law mandates other new obligations upon doctors beyond patient care.
Tweak the numbers a little if you will, you are still looking at a big mismatch between how many people want to see doctors and how much time is available within which to be seen, especially if follow-up care is needed. More and more care by necessity will come from nurse practitioners and physician assistants, there just aren't enough doctors to handle the increased demand with restricted supply.
My new doctor isn't taking new patients and hasn't been for awhile, the only reason she agreed to accept me was that my previous doctor had been part of the same practice as hers and he retired from seeing patients (he still works part-time teaching). He didn't want to retire either, he told me at our last visit (end of last year) that he loved the practice of medicine and enjoyed seeing patients, he was reluctantly leaving patient care because he wasn't willing to put up with the new rules and regulations being forced upon him against his better professional judgment. Those were his words, not mine.
Provider networks are getting smaller at the same time more people are looking for practitioners. I've read about several small towns who will be left with no doctors whatsoever because the sole practitioner in town is unwilling to comply with the new provider mandates.
When people bring these facts out, the typical response is that PPACA was meant or intended to blah blah blah and how could anyone criticize it based on such noble ambitions? well, if it doesn't work in practice, that's empirical data. Sensible people adjust their behavior when they get data telling them that something is going wrong. Idealogues insist that we must keep doing the same thing, only harder and more of it. The two sides are talking past each other entirely and neither one is hearing what the other is saying. It's a situation in which both are "right" because they are talking about two different things entirely.