The reality of today's world is that information has a value. It has become a product that can be bought and sold. Large online genealogy databases have discovered that there is a cost to putting records online and that once online, they can be sold through subscription websites. This is simple economics, if you put up a billion or so digitized or indexed records online, people are willing to pay to see them. So why would you give away free what costs you to put online? Once the record repositories understood that their records had a monetary value, could they continue to give them away for free? Once FamilySearch.org realized that the records accumulated since 1938 had a real monetary value and not just a research value, agreements with commercial online genealogy databases was inevitable. For the participants, it is a win/win situation. FamilySearch gets the acquisition, indexing and digitization of the records subsidized and Ancestry.com gets even more records and becomes even more valuable.
Do the genealogists lose in this situation? It depends on whether or not you put any value on your time and the ability to find records about your family. There may be whole classes of records that will no longer be available to FamilySearch because governments and other record repositories will not donate their records to FamilySearch merely for the preservation and availability of a copy. But once those records became valuable, they will be more willing to share them for whatever price they can get given market conditions.
A more suitable question, should be why do genealogists (and others) feel that all of the records in the world should be freely accessible? Where did the idea of free come from? If you live in a city such as Mesa, Arizona, you have access to a "free public library." Anyone who lives in Mesa can go to the library and check out books or use their resources, including computers and online access, for "free." So who pays for this service? Everyone of the property owners in Mesa or anyone who purchases anything in Mesa subject to sales tax. If you buy things in Mesa or live in Mesa, you help pay for the "free" library. So who pays for the "free" genealogy records online. The answer is a little more complicated.
Anytime records are online, some one has to pay for making them available and keeping them there. In the case of FamilySearch, those who pay are those who contribute time and money to FamilySearch, either directly or through donations to The Church of Jesus Christ of Latter-day Saints. Who pays for Ancestry.com? Easy, the subscribers and probably a few other people for advertising and revenue from the sales of products and services on Ancestry.com and their other websites and businesses. In both cases, you can use the records for "free" if you want to go to a library or in the case of FamilySearch.org, anyone can use the records for "free." But remember, some one had to pay for the records. If I don't subscribe to Ancestry.com, for whatever reason, I do not end up subsidizing their websites like I do the public libraries in Mesa or any other community. If I don't want to pay Ancestry.com I don't have to, just as if I don't want to live in Mesa, I don't have to.
But one way or another the huge cost of putting genealogy records online and keeping them there has to come from somewhere. So being upset because there will be more records and that there may be a direct cost associated with the access to those records is like hoping money will fall out of the sky and land in your bank account. It isn't going to happen in this world.