Prius batteries have been holding up well. Honda (doesn't matter what model) batteries, not so much. Don't be misled ... the amount of energy that a vehicle uses over its normal lifetime to drive it down the road, exceeds by a huge margin (~10 times) the energy that it took to build it, and the hybrid battery packs are an insignificant part of the weight of the vehicle. (all-electric car is a different story.) The hybrid Jetta weighs about 200 lbs, i.e. 6%, more than the standard one. The energy taken to manufacture is pretty close to in proportion to its weight, so if it takes 6% more in the beginning to manufacture it but that results in 20% less over its lifetime ... that's a worthwhile tradeoff. (1.06 + 8 is less than 1.00 + 10)
Improvements in powertrain efficiency have been offset by increases in vehicle weight and power; there have been other posts about this recently. Your '86 Jetta won't come even remotely close to passing today's crash tests. Frontal offset impact was hardly a consideration back then. Side impact ... good luck. On top of that, people now expect a level of quiet and refinement that did not exist back then. You couldn't sell a car now that was as noisy inside as that '86 was. No one would buy it. And, everyone wants air conditioning, and navigation systems, and fancy stereos, etc.
Then there's the matter of the enthusiast magazines complaining about anything taking 9 seconds or more to 60 mph as being "slow". People have been brainwashed about this. The average person takes 15 seconds or more to do it and seldom, if ever, uses the extra power.
You're right about the days of the home mechanic being numbered, though.