Power consumption is a critical factor in many systems, and having control over the power supplied to sub-systems or remote modules is a key technique; as is avoiding Thevenin sources where ever possible, dynamic control over clock speeds, and even capacitor leakage current for ultra-low-power products.  Conversely, whilst I2C will never set the low-power world on fire, it’s still a ubiquitous nuts-n-bolts inter-chip interface, which some “engineers” still get so wrong (*cough* I’m looking at you, high-profile SV-based drone company no longer making drones *cough*).  The world of electronics is a dense and overlapping landscape of possibilities and solutions.