The strongest point of Bitcoin is its decentralization and this is why the scaling debate is such a big issue.
Why is it that we're now ok with centralization ? If lightning leads to a few centralized hubs then we need
to design it in such a way that this won't cause issues further down the road.
What do you mean by 'few'? More than likely LN hubs will be orders of magnitude more numerous than mining pools are now.