Why do so many fans love it?

[Asimov's] Foundation series is much beloved by many SF fans, although it suffers from a ubiquitous and debilitating dryness of tone. It is almost entirely composed of dialogue, often of an expository or explicatory nature; there is little description, a fact which renders the sequence visually inert; and the characterisation is rudimentary. Why do so many fans love it?

A. Roberts, The history of Science Fiction (2005), 197

I love it. It's proper grand concept Science Fiction, though the maths is all wrong. 

[Tinsel] possessed all the qualities of silver plus one more – pathos

Flaubert once said that he liked tinsel better than silver  because it possessed all the qualities of silver plus one more – pathos. … Of all the pulps, SF pulp is the most tinselly: partly in the sense that its content was more dazzling, starry, most likely to lift its readers’ eyes, metaphorically, to the brilliances above us; but partly also in the sense that it was aware and even revelled in its own cheapness.

A. Roberts, The history of Science Fiction (2005), 175

Science-fiction fantasy (dragons are common, the gizmos are less plausible and may include wands)

"Science fiction" is the box in which her work is usually placed, but it's an awkward box: it bulges with the discards from elsewhere. Into it have been crammed all those stories that don't for comfortably into the family room of the socially realistic novel or the more formal parlour of historical fiction, or other compartmentalized (sic) genres: westerns, gothics, horrors, gothic romances, and the novels of war, crime and spies. Its subdivisions include science fiction proper (gizmo-riddled and theory-based space travel, time travel, or cybertravel to other worlds, with aliens frequent); science-fiction fantasy (dragons are common, the gizmos are less plausible and may include wands); and speculative fiction (human society and its possible future form, which are either much better than what we have now or much worse). However the membranes separating these subdivisions are permeable, and osmotic flow from the one to another is the norm.

M. Atwood, In other worlds: SF and the human imagination (2011), 115