As an ecological dilemma, burning a lot of energy via PoW seems not to align with the progressive agenda of an aspiring global cryptocurrency.
Though your first sentence is not actually a question, I shall refute your statement. Energy is never burned using POW or wasted, every single bit of it serves an extremely valuable purpose, no miner is wasting energy, they all get paid for their contribution and that contribution is proportional to the usefulness and value of the network as a whole. It uses proven and sound principals to reach an outcome while ensuring it's integrity as a 100% decentralised autonomous network unlike PoS which has major deficits in it's decentralisation and viability as a network that can resist attack and maintain it's security and integrity. Monero's POW is however designed to make it less efficient to centralise as it has a large memory component, so this should mean mining on PCs and GPUs will be viable for at least several years to come, and then there is the option of stalling the jump to ASICs even further by employing cuckoo POW which is even more memory heavy (and results in much faster transaction verification times). Ecologically the argument is moot as Monero is not a system requires infinite growth, it will reach an equilibrium where the number of transactions, nodes, and services it can support will peak, and miners will stop growing with that. Unlike other financial systems that demand higher and higher consumption via debt to keep the financial wheels turning, systems that utilise PoW do not have such antiquated mechanisms and will reach equilibrium eventually. They are able to grow and shrink as needed to support the economy that it underpins and have no fundamental requirement to grow at all costs. Once big enough, their resource requirements will stabilise.
As to your actual question, those features are already in place in the monero-wallet-cli, it only needs to be specified when restoring your seed. As long as you know the blockheight from which the first transaction appears, you can skip scanning most of the blockchain up until that point.
Let me present some arguments.
As an ecological dilemma
Let's consider the scale of mining operations energy consumption. I will take a random mining rig consisting of 6 AMD 480 GPUs, and giving 3450h/s for my calculation. Each GPU has a TDP of 150W, and that gives us 261W/kH. Actual Monero network hashrate is 30MH/s and market cap. 90mil USD. From there, the power currently used to mine Monero amounts to a total of 7.83MW. For comparison, that's about 1/10th of the power available to one big container ship. We can see that, at the current scale, Monero network power consumption is insignificant.
Now, let's scale it up. I will assume linear scaling just to keep it simple (ignoring reducing block reward and supply growth) but it shouln't matter much for estimating the scale. Let's imagine one day Monero becomes a big currency used widely. Market cap. of 1 trillion USD seems reasonable at that point. With linear scaling we get to 87GW. Now that's some serious power. That kind of power would be equivalent to about 87 nuclear reactors or 870 square kilometers (30x30 km area) of solar panels, if you want to go with renewable energy. You think that's big? Let's put it in perspective, it's 0.7% of total world energy consumption, so yeah, it's big, but not humongous. Don't forget, at this point we're talking about a currency as big as 1/4th of USD. We could ask how much power is needed to maintain and support the USD system? I'd like to give some numbers as an answer but don't have an idea on how to calculate that. Let's leave that to imagination of the reader. Remember, though, that I didn't go much in detail, so for 1 trillion USD market cap, we'd probably see less power needed.
In any case, if the world energy production moves to ecological sources, then spending the energy for whatever reason will be ecological as well.
burning a lot of energy via PoW seems not to align with the progressive agenda of an aspiring global cryptocurrency.
Why would we consider that the energy is burned? The energy is spent to ensure integrity of the ledger. It's spent with a purpose of maintaining correct records, as is all the energy used by the current financial institutions.
The thing is, humans spend energy for various things: like driving a car, cooking a meal, building a ship, surfing the internet, making wars, making love. We could use the same argument and say that any of those purposes is actually burning the energy because we don't feel like the purpose is worthy enough. That's where economy and market forces come into play, where resource allocation is just the current state of our global game.
I agree that it makes sense to improve the efficiency, which will be driven anyway by those involved in the game. However, PoS can't work for that purpose. See here for more info.
It's because with PoS you're trying to build a closed system, where the security is supposed to come from within the same system. That means it could easily collapse and converge to some state from where it couldn't recover (without outside interference). This has roots in laws of physics, which can't be cheated. A system needs to use energy from the outside to run, otherwise we're talking about a perpetuum-mobile which can't do anything useful other than repeat some loop of internal states over and over again. PoW is the only anchor to the real world, otherwise a blockchain would be nothing but a simulation with no way of knowing which one is the right one.
At the end, I like to say that PoS is like trying to lift yourself up by pulling your own hair. It can't work because you aren't spending any energy by doing it - there's no external force acting.