Angiosperms have dominated the land flora primarily because of their -

Angiosperms (flowering plants) are the most dominant and diverse group of land plants, with about 2,50,000 species.
They are found in almost every kind of habitat, from deserts and high mountains to aquatic environments, and range in size from tiny Wolffia to tall Eucalyptus.
This dominance is mainly due to their great power of adaptation to diverse habitats: efficient vascular tissue (vessels in xylem, companion cells in phloem), varied forms and life cycles, flowers that attract many pollinators, double fertilisation, and seeds protected inside fruits with many means of dispersal.
Producing many seeds, self-pollination or domestication by man alone cannot explain their dominance over the whole land flora.
So angiosperms dominate mainly because of their power of adaptability in diverse habitats.