I would agree that this would be a sensible thing to do.
Most people download the client from a central place anyway so I don't see much added risk including an up to date block chain.
People can, and do, audit the software— even the binaries due to the use of a deterministic build process— so any replacement with a compromised version has the risk of detection. At least as things are currently constructed, an opaque blockchain wouldn't have this property.
Discussions of including the blockchain are ignoring the real issue too— initial syncup is slow because the chain validation is slow. The validation is slow due to IO related implementation issues.
Once this is fixed there will be a lot less cause for concern. Beyond that, the software should eventually make validation and downloading decoupled so that it could go on in the background— making the client usable even while downloading/validation is going on. This would be much better than making the install file a gigabyte.
In any case, it's easy to propose things— and the idea that the package could include a copy of some blockchain, with the according loss of zero-trust hasn't failed to occur to pretty much anyone— why not sit down and spend some time trying to improve it?