From the "old universe" point of view: what the Imperial fleet is actually lacking are more small ships.
Looking at the original movies it is clear that the Empire brings in ISDs and more ISDs when it gets tough, because those are the scariest, hardest hitting, squadron carrying, superior allround vessels.
To free up those ISDs from Outer Rim duty, where not much is happening to rectify the use of a huge ship like this (those things are expensive, you have to save some money if you also want your super-huge planet destroying superweapons built), you need your small patrol vessels to handle the occasional pirate incident.
The NebulonB was such a ship, the Striker and Carrack cruisers. The Gozanti really is the only Imperial ship available to fall into that category.
The Raider is special as an FFG creation, useful for anti-fighter support. It is a cool design and I like it well enough, but in itself it lacks something that the old Lancer frigate had: credibility of the universe as a whole.
Let me explain: During its creation, the Star Wars universe was especially credible because of the used look, the Falcon falling apart, dirty, scum-ridden spaceport, jury-rigged repairs on your old Y-Wings and so on. The Lancer and also the Assault Gunboat with their truly boring designs were EU creations that carried the spirit of a used and dynamic world with them. They were ships the Empire put together in a hurry as a reaction to Rebel hit-and-run attacks which completely exploited the Imperial military doctrine. Put together as fast as possible as a reaction, boring design, mediocre overall performance (slow speed etc.), but it gets the job done. Somewhat credible background, this adds to a dynamic universe where actual new developments occur based on short term need.
The current design philosophy seems to be more along these lines: Imperial stuff must be triangle-shaped because it looks cooler, all Rebel fighters have been along all the time, just in different cells (A-Wings) and have bit been freshly developed based on need and so on. It just feels kind of static.
Wow, this got long and off-topic in the end. Sorry for the rant. I am glad that Star Wars is very much alive and going strong, I just find the universe changes lacking in some points. Please don't kill me in the replies!