Thats not the point. I don't want to purchase mechs and weapons that I dont ever plan on using. Those creds and acoins are just being wasted getting to the next tier so that I can spend more creds and acoins getting the actual mechs/weapons. As Commrad mentioned, you will have to upgrade mechs and weapons to get to the next tier. Do you know how much it costs to upgrade a mech to 4-5 stars? Let me tell you: it aint cheap.
I presume that, technically, it wasn't that easy to skip some Tiers, and if you have an end-game account, you might have already acquired Mechs from each Tier. In this way, the New Progress System doesn't change the flow a lot but makes it more systematic