It's primarily a matter of economics and changes in building codes. Balconies require more complex construction with cantilever beams, which is more expensive and harder to install, while loggias are built into the house volume and cost less. Plus, buyers these days often prefer loggias anyway - they're warmer, protected from wind and rain, and easier to glaze without extra permits.
As for the complete absence: it's about maximizing usable floor area that can be sold or rented. Not every project requires balconies by regulation, so developers simply don't build them if they're not critical for sales. In smaller buildings this really is cost-saving, but in the premium segment balconies remain - simply because solvent buyers expect them.