For some people, brand recognition does play a role in real estate decisions. However, I think the preponderance of such chains is more about agent value than customer value.
The economies of scale found in large companies allow them to field better initial training, greater marketing power, more networking opportunities, free continuing education (with an actual dollar value), and all kinds of other tools that are generally big selling points for agents. I interviewed with our local Keller Williams office when I was in RE school, and while I did not end up taking that route, I could see the draw for people with other priorities. If you do a high enough volume of business, you cap out and get to keep 100% of commissions, and so the higher splits become a non-issue.
It'll never apply to me, since I only hold a license to do my own investment deals and occasional friends/family jobs.