Interesting points. Here is a few things you'll miss choosing Route 53 over ELB:
* HTTPS termination.
* Autoscaling group management. By connecting an ELB to an autoscaling group, the logic of registration and deregistration is fully managed behind the scenes. With route53, you have to implement it yourself.
* Minimum autoscaling group size. If you enable ELB health checks, you can rely on the ELB to maintain a group of instances of constant size.
ELB's HTTPS termination is mediocre and, last I checked, doesn't offer the best ciphers. A year ago It was impossible to get an A+ on ssltest https://www.ssllabs.com/ssltest/ using ELB to terminate SSL.
Not to mention it still needlessly includes a ton of dangerously insecure ciphers just begging to be misclicked.
The current default, ELBSecurity Policy-2014-01 [1] enables ECDSA/PFS and is close to the Mozilla TLS recommendations [2]. Getting an A+ on the Qualys test requires the HSTS header [3], which isn't an ELB issue.
ELB scales horrible and can not scale to even tens of thousands of connections per second, let alone handling spikes of 100k/sec simultaneous connections. Even if you get AWS to prewarm to ELB at a higher peak rate, if you spike over those limits you will drop new incoming connections. HTTPS termination is trivial compared to a requirement to be able to actually handle hundreds of thousands to millions of simultaneous connections per second.
Actually, ELB can scale pretty well... but... you need to file a form and they will up your ELB capacity. Totally ridiculous; the situation with CloudFront.
Is https termination really worth mentioning? They'll still be running some type of web server (nginx, apache, whatever) and enabling https termination there is probably easier than going through the elb wizard.
* HTTPS termination.
* Autoscaling group management. By connecting an ELB to an autoscaling group, the logic of registration and deregistration is fully managed behind the scenes. With route53, you have to implement it yourself.
* Minimum autoscaling group size. If you enable ELB health checks, you can rely on the ELB to maintain a group of instances of constant size.