Redirecting from HTTP to HTTPS is not a bad thing. What is bad is relying on it as if it was a security feature.
This redirection is a lighthouse, meant to allow ships lost at sea in the storm to understood where they are and, with luck, give them a better chance to reach a safe haven. Nobody claims that lighthouses make storm disappear; they just improve probabilities of a happy ending for bad conditions.
The only bad thing that can be said about an automatic redirect from HTTP to HTTPS is that it breeds complacency. If a user errs, e.g. by trying to access the Web site as HTTP instead of HTTPS, the automatic redirect allows him to persist in his mistaken ways, hiding the fact that his inappropriate URL exposed him to the vindictiveness of Internet dwellers, some being quite proactively evil at times. Disabling this redirection could be construed as being more pedagogical. However, this point of view is somewhat unrealistic; most Web site owners are in no position to educate users. What they want is to grab the attention of potential customers. If you begin to make access to your Web site more difficult, then they will just go away; they will not be educated in the slightest way, and business will suffer.
"That which does not kill us makes us stronger." A catchy phrase from a more-than-half mad philosopher; but not necessarily applicable to the general public as an educational policy. The problem with making people stronger by trying to kill them is that sometimes you succeed -- to kill them, I mean.
As mr spuratic explains, to really makes things better, browser should use HTTPS by default; ideally, the whole Web would be HTTPS-only: if browsers try HTTPS first but fall back to HTTP in case of errors, then an active attacker can simulate the failure and force a fallback. DNSSEC coupled with appropriate SRV records could advertise, in a secure way, that a given server should be used with HTTPS only, but this will work reliably only when... it will work everywhere (same bootstrap problem as IPv6).
In the mean time, a redirect will bring stray sheep to the stable even when the sheep are completely unaware of the wild beasts who roam the night-time countryside. This is usually considered a more efficient method than trying to teach sheep not to stray.