The doctors I've worked with use medical terminology (full of big words like "trilineage dysplasia") because they need to be precise when they work with each other and when they exchange data and research papers.
Their challenge is to meet laypeople at least halfway. Clearly, some doctors are better at this than others, and patients who only listen and nod their heads may leave doctors unable to tell which parts you understand and which parts you don't. Yeah, there are no doubt some bad apples who don't care to explain things to you in terms you'll understand, but I think they are the exception and that the time pressure of short appointments is at least as much to blame.
Bone marrow biopsy reports are written by medical specialists for other medical specialists. It's only in recent years that we patients have started asking for and receiving copies of them. It's not a surprise that we can't easily interpret them. We could sure use some medical-to-English translation software!
It's the same in my profession (computers). We don't speak in computer lingo and our infamous acronyms to impress people. If I say "I need the software for the database" to my coworkers they won't know which type of software I need for which type of database. I have to say "I need a single-tier ODBC driver for the RDBMS" instead. It's the same with other technical fields (biologists, financial advisors, architects). I can hold my own in some of these fields, but when the auto mechanic explains what's making that funny noise in my engine, he sometimes gets too technical for me and I find myself silently nodding my head.