More payments will naturally flow through nodes with more channels and liquidity. For example, an LSP will route more traffic than a raspberry pi with two channels. This is inherent and good.
The protocol does not give a node a reliable way to find a feasible path to the destination. Each channel a payment is routed through adds a risk of failing due to insufficient liquidity, which means longer payments routes are exponentially less likely to succeed than shorter routes. Generally speaking, there are two mitigation's to this: make bigger channels and prefer shorter routes during path finding. This is bad centralization.
Yes, for two reasons.