However you turn this around, transaction spam is a major problem. On the other hand ; you may want to ask the question on who is to blame?
It's funny how this is happening since the fix for this was proposed more than three years ago by Coblee, why it didn't get implemented is beyond me.

cheers

Proof of Stake is not the answer, because it promotes the idea of rich getting richer, which is against bitcoin's agenda.
The solution to this problem is for developers to start developing, or we can close the curtain and end this one-man-show.

cheers

The miners are greedy, that's why many blocks aren't filled.

First, some miners did not yet found out how to set the setting that 1MB blocks are allowed, i have read so. 750KB blocks following. 

Second, some miners only accept transactions with big fees. They want to enforce people paying higher fees.

Third, some miners implement no transactions at all. They want to have an advantage in propagating their own block. Because it's way faster to propagate an empty block through all nodes, and reach >51% acceptance for that block than sending a 1MB block through all nodes. Such a small block could orphan a big block since he is faster.

So blame it on the greediness of miners.

The miners are prioritizing transactions based on how large the tx fee paid is verses how much of the block the transaction will take to confirm. If someone were to pay a higher fee on a per kb basis then it will most likely receive a higher priority then someone who pays a lower fee on the same basis.

Transaction fees on a per kb basis are generally higher then they were in the past and very few no fee transactions are getting confirmed currently. Many wallet programs will advise you how large of a tx fee to include based on the size of the transaction, however this is almost always based on the setting you have set (or what are set by default if you did have not changed such settings) so if too low a setting is selected, your wallet software will advise you to include too low of a fee.

They look nice and full now, but when the post was made the blocks were going through like 1/3 full and other fuckery like that.

I don't think the miners really care that much about transaction fees right now.
I think they care most about the block reward.

However like you said: Why spend the same resources on transactions with little fee's, if you can spend that same resources to get to the juicy transactions with the higher fee's.
It's business

I think it will become worst in the near future. {2016} We will have a halving of the block reward, and the miners will need more fee's to make up for the reduced coins.

This experiment already gave them the taste for more fee's and also the information on how to do it.

I predict a increase in the use of alternative payment channel services like Xapo, where off-chain transactions with instant confirmations can be done. This might be the only method to counter higher

miners fee's, from people sabotaging the blockchain for their own benefit. These services will have to increase security for that to happen, and they will also need to bump up their protection against Doss attacks. {A lot of pissed off miners will start to target them, to force people to use the Blockchain} 

By the time fees become important for miners the fees should be enough.
By then I expect Bitcoin to be mass adopted therefor fees should be adequate.
I doubt I will be around to witness that by that time, but my guess is that, that is how it is going to be.

Who says that miners need to earn the same they earn now? The fees are nowhere near replacing the block reward. So miners will have a hard time and they need to stop using some miners.

Advancing tech cant help very much there.

It would be really hefty when miners try to get the same reward they get now. They would need to add 12.5 Bitcoins in fee per block. That would be deadly to bitcoin and to the miners at the end. But when i see how levelheaded scammers and forking miners are acting then i wonder if they would think about that at all.

you COULD buy an asic and start mining....