Andre, your rationale is broken.
Let's say tomorrow morning block size is 10mb.
I spam it to "full blocks". After all, fees are dirt cheap (even now, 42k txs were processed in the last 24hrs for near zero fees at the 0 to 9 satoshi range -
https://bitcoinfees.21.co ) since there's around 0.7-0.8mb actual demand (or at least pretending to be actual by paying 10+ satoshi) and no practical fee competition for the rest 9.3mb.
So once I do that, I come and tell you that there is no room for new users because txs are maxed out.
Spot the fallacy.
No, it's your rationale that is broken. Because you assume that low paying txs are spam. But if they are spam, why pay anything? It's like saying the passenger who bough a $10 plane ticket isn't really going anywhere -- he's just spamming the airplane, because his ticket is so cheap (look! 42 of the 250 passengers had a $10 ticket on the last flight!). I disagree with your assumption. I think cheap customers are still real users of the airline. And by selling their seats to others who pay more, you are not flying more passengers. You are not increasing the user base.