I think the idea is that he simply isn't good enough to start for a top tier club as seen by how he wouldn't be an upgrade to any of the strikers you just listed out ... So even if there was space available, they probably wouldn't buy him and look at other options first as seen by how Atletico bought Mandzukdic even though they probably were offered Lukaku
Not really. Again assumptions with probably offered Lukaku. I'm done right at the start. Don't bother.
When a good player comes along top sides take the gamble on them, Monaco have the James money in their pocket now with only Falcao as main striker and in the Champions League next season? Spurs have only Adebayor, Atletico only now have Mandzukic and money to spend, Liverpool have money to spend and need to bridge the gap left by Suarez leaving. Top clubs would have taken him if he was worth the risk.
Lukaku is leaving Chelsea for one reason, he wants to be the first choice player.
Also not every club has russian or oil money to burn 30 Million on a player not needed tbh. Not a dig at any club, just stating the fact. All clubs work on a budget, they just don't throw money at a player when they have good enough options at their club.
Also Lukaku will never be good enough for Chelsea if he isn't given chance.
I know Chelsea fans disagree but he is making right choice for his career.