I believe the devs are working on the size of the blockchain, but it's not at the top of their list, and rightly so. They have bigger matters which require their more immediate attention.
You're correct to point out the growing size of the blockchain, but it's a relatively small problem amongst others.
100TB to 1,000TB bandwidth requirement for full nodes in just 4 years time is not a small problem. Who has a data plan that can allow that, even unlimited plans have a fair use cap?
There is very little the devs can do about the growing size of the blockchain. Data is data.
Multi sig, for example, will counter any voodoo by the devs to reduce the size of transactions.