What's up with lousy bass on classic rock recordings?

As others have noted what mix/pressing you listen to will matter - a lot. One reason is most mass-market produced albums in the 50s-70s were made to be played on one piece consoles with speakers and turntable all in one cabinet. A big bass presence would bounce the needle right out of the track.

I have a double Wally Boston debut and a 1st pressing Van Halen and the bass (low end) is awesome, perfect! I’m really only "Vinyl"  in the house for music internet radio for my sports and talk shows, CD or Mp3 in the truck for music. VTA and tracking force is dialed in on my turntable and level, just finished the Utrasonic cleaning project for all my LP records.

I have 2 systems, one with Fritz Carbon 7 SE's bookshelves and a SVS sealed 3000 model, and a another with Tekton SE double impacts with an SVS sealed 4000 model, listening to just R&R loudly, NO VINYL, just digital CD and stream Quboz.  AC/DC, Def Leopard, Led Zeppelin, Rush, etc. Bass is just GREAT, Dynamic, tight, and accurate, and as others have stated, you will also run into some disc's or songs that just aren't there sonic ally, as they have mentioned, just poor recordings. Robert TN

Use a sound meter app like decibel on iPhone to measure the actual frequency response with a variety of recordings. Are you seeing response down below 40 hz or so with the recordings you know have extended bass? If not adding a proper spec’ed powered sub that is up to the task for your room and mixing it in using same sound app to measure while adjusting the sub to fill in the missing low end will make a huge difference. The key is to measure, see what’s missing and get a good sub big enough to do the job and fill in the low frequencies, not just add more of what you already have otherwise. After that if you don’t hear the bass it’s just not there to hear in the recordings you expect it to be. That’s assuming electronics used  are up to the task of delivering full range sound down to 20hz which is generally regarded as the practical low end for human ears.  Most good quality modern hifi gear should be up to the task. 

@mapman I use an SPL app on my iPhone routinely to protect my hearing and yes the low end down to 31Hz is prominent.

Did you look at my system?