(tl;dr The new mining barges are excellent. CCP converted an upgrade path into roles. Roles are far superior to upgrades, are more suited to the EVE Online concept.)
That's why EVE Online has the longevity that it does. CCP doesn't have to introduce new ships with every expansion cycle, because we continue to fly a very wide variety of ships, not because we have too, but because we want too. We don't give up flying our current ship simply because we now have the skill points to fly something that requires more skill points. Battleships aren't better than frigates. They're simply different.
Skill points aren't gained simply to vacate our current ship to jump into the next ship in some upgrade path. We aren't striving to reach some ultimate ship. CCP doesn't have to keep introducing new ships, because there is no ship that trumps all other ships.
Upgrade paths do exist with certain module groups. If you can use a Damage Control II, there's really no reason at all to use a Damage Control I. But if you can use a MicroWarpdrive II, you're likely still going to stick with tech one versions, because of fitting and cost considerations. With modules, there are certainly items that are better than other items within a module group, but EVE gives us a variety of valid reasons to use lesser items over their better tech 2 variants.
Where an upgrade path has existed within EVE Online, and been most glaring, is with mining barges and exhumers:
Mining Frigates < Procurer < Retriever < Covetor < Skiff < Mackinaw < HulkThis is all about to change. CCP Ytterbium's most recent devblog announces that mining barges and exhumers will be redesigned. No longer will the upgrade path exist, each ship will now have a well-defined role to play. (As well, all of the current mining frigates will be replaced with a new ORE frigate.)
One of the complaints from Hulkageddon victims is that none of the mining ships offer an option of defense. Given how dangerous mining can be in New Eden, it is a little odd that ORE didn't design for demand sooner. ORE finally came around, their delay has been but a miner inconvenience. Players will now have their heavy defense mining barge; it will be at the expense of cargo and yield, but there should be trade-offs.
|Ship Type||Resilience||Cargo Bay||Mining Yield|
The table is an oversimplification. The Skiff's resilience will likely be off-the-charts compared to the Mackinaw. None of the frigate's capabilities will be comparable to the barges and exhumers. That said, the table does give a quick reference to the design differences between the ships.
So what are the roles? Frigates, for fast agile mining fleets in very dangerous locations. The Procurer/Skiff for solo mining in high-gank areas (the ship of choice for Hulkageddon). The Retriever/Mackinaw should be a capable solo and small fleet ship in highsec and lowsec. The Covetor/Hulk for fleet mining operations with Orca support.
These changes won't cure all the mining whining. There'll still be the knuckleheads who'll go for the highest yield ships and fly them solo, no matter the inherent dangers in doing so. But with these new roles, CCP can now rightfully tell the knuckleheads to HTFU and use a Skiff. CCP can ignore their desperate forum posts, let the playerbase deal with them the way the playerbase best deals with people like this (wardecs!)
So, yeah, roles are greater than upgrade paths. This is a very welcome change to EVE Online. So, congrats to CCP Ytterbium and the other devs working on the new mining barge iterations.
 An argument could made concerning Skiffs and Covetors, but the Skiff is certainly more versatile, even if it lacks defensibility and module slots. Either way, even if we flip Skiffs and Covetors in the list, a glaring upgrade path does exist.