Yes, the HOA members can vote to change the bylaws and CC&Rs of a community. We have seen a lot of these changes in Las Vegas over the past few years.
After the real estate market crash, we had a flood of investors that were purchasing properties and renting them out in neighborhoods that were historically owner occupied. The associations "fought back" by limiting the number and term length of rentals. A few HOAs even went so far as to outlaw rentals entirely.
The only thing you can do is check into whether the proper procedures were used to change the by laws and CC&Rs in your community. Actually, many associations pass restrictions without using the proper procedures an, if so, can be challenged. Your only other recourse would be to sell the property you have and replace it with one that is in a community without those restrictions.