Since the building that are always available in the store are now basically little to no help to build your IPH... How about increasing the maximim upgrade level of those buildings to 15? It seems like a small odd change, but it may prompt people to increase their total building numbers and thus have the ability to increase their IPH. Yes, we all agree LTB's are the wave of the future, and the best IPH builders...however if new people are whining about not getting higher incomes, why not make some improvement to the regular buildings. Every other aspect of the store has been improved.
I would love to make my Laundromats Lvl 15, with 10k-25k, every 5 minutes. (and yes obviously not just the laundromats, but ALL regular buildings). Imagine a LVL 15 Nightclub...fantastic for all!