Lukaku isn't playing for good reasons.
Firstly, it's the beginning of Mourinho's first season back. He said himself he was glad to still have a core of experienced players. Hence MVG and Lukaku haven't really had a look in as Jose has wanted to get off to a solid start.
Secondly, Lukaku rarely started last season, he was used as an off the bench battering ram to come on, and it worked wonders for WBA. So it's not fair to presume he'll start the games for us at the beginning of the season when we're a top team, and looking for a solid start. He's still 20, Torres and Ba have experience.
Lastly, most of the pundits believe Jose is doing it on purpose. Lukaku has given numerous interviews stating his determination to break into the first team. He's young and 'hungry', he will not be losing confidence. The Chelsea TV staff believe Jose is holding him back so he gives it all when he starts getting his chances to start, which will be sooner rather than later. Look at the work Ba put in against Villa. It wasn't effective but the guy never gave up running. They all know competition is fierce.
Lukaku and MVG will get their chances when things settle down, presumably after the internationals. We rejected on offer from Ajax to take MVG. They're both in his plans. Stop over-reacting.