1) This "limitation" is due to the star schema model and SAP HANA's Analytic Views are optimized to support this model (including its limitation).
Compare that to other platforms and you'll find similar restrictions (e.g. the STAR TRANSFORMATION optimization also is based on a single fact table).
2) You're mixing stuff up here and generalize far beyond sense. How you store your data is not necessarily dictated by a specific way of querying the data later on. Query performance is one aspect but by far not the only one.
Analytical Views are not the only development tool in SAP HANA - you may want to consider the many other options if AVs are not the optimal choice for your use case.
- Lars