I wouldn't criticise the new Hornby Junior range, if it's anything like the recent Marklin "My World" trains. They are excellent for young children, robust enough to be laid out on the carpet like the old clockwork trains and can be left to young children to play with on their own in a way you couldn't with a regular Hornby train set.
The Marklin trains run on regular H0 track so there's some kind of upward compatibility into "real" model trains - there's even an adaptor truck from the simple magnetic couplings to regular H0 ones.
Given the rate at which the Marklin range is expanding, it must be doing quite well, and it seems very sensible for Hornby to emulate them.
In short, I see this as a very positive move...assuming it's as good as the Marklin product.