The nice thing about a full-featured MTA with real local queues is your mail will still pass through when your ISP decides to do a big advertising campaign without upgrading its network first.
I don't question the value of a full-featured MTA for an advanced user. I just don't see it as being a required feature for a new user.
Presumably the people installing Fedora who can't configure sendmail are either home users (who have a full-featured ISP to operate a real MTA) or business users operating behind a company MTA. AFAIK, Fedora isn't being pushed as an "MTA training platform", so there's no need to keep one in the Core product when it's tight for space. And if it's not tight for space, one could still use a very simple outbound-only queuing MTA for the default and make Postfix/Exim/Sendmail choices for advanced users.
