The problem with delaying blocks is the following.  As a simple user, you may feel personal satisfaction by not relaying the block and it may not affect you in any other way.  But as a miner, you are in a difficult situation when you receive a block that you dont "like".

For as long as you plan to dislike it, you cannot mine on top of it - because your potential next block would be waste without the "evil" block. It is chained to it and eventually you will have to publish the "evil" block along with your own next block.  To make things worse, your chances of success are higher when you relay the "evil" block as soon as possible.  Otherwise you not only depend on your own luck (difficult enough), but also on the luck of the "evil" block (which you have tried to diminish).

Therefore, if you dont like the block, you must not mine on top of it.

This is a very risky strategy.  Other miners may not be as picky as you are, and then your mining efforts may end up waste.  You are intentionally mining on an old block, knowing that a newer block exists.  This can only play out well, when you are absolutely sure that most other miners ignore the block too.

Every time an "evil" block appears, the chances of an orphan produced by (self-proclaimed) "legit" miners raises.  It can be seen as a seed for orphans.  And I mean an orphan of "legit" work, not only the "evil" work itself.

(Remember that I am talking all this under the premise of the poposed intentional relay delay)

Although the percentage of seeds is only 15%, the chance of an orphan arising from it may be much higher.  It depends on the adoption of the protocol change and also on the individual configuration that each miner chooses.  We could very well face a situation where everyones own mining effort has a 50% to be orphaned after each seed.

Effectively every miner would pay a very high price for a just slightly better service.  At 15% seeds and 50% chance to orphan, EVERY "legit" miner would loose 7% income.

A high price to pay.

To pay for what?  Well for the slightly better service quality I suppose.  "Slightly better", because a TX can make it 15% faster into the chain.  However, there is also a negative effect, which is the constant rate of orphans and reorganization of the blockchain.  This could be seen as another kind of "Dos" or attack on bitcoin.  It makes 1 or 2 confirm transactions very unreliable, and can also affect 3 confirm TX or higher.

People who rely on low-confirm transactions will now have to wait CONSIDERABLY longer, not just 15% longer for the first confirm and 0% longer for every subsequent confirms.

We have already seen runs of up to 4 or 5 consecutive blocks with no TX, all from the same source.

The higher price paid by miners (in form of extra electricity with less BTC reward) may actually make the overall service quality worse.