Because back then segwit did not include a capacity increase. Now it does. Segwit also allows for extension blocks which can be activated with a softfork, so the limit can be increased in a safer way than doing a hard fork, when needed in the future. when Weak blocks/IBLT are developed, increasing the limit will be much safer, as these will reduce the resources required to run a node.
The core plan for scalability is as follows:
Short term: Segwit, which makes the Bitcoin protocol extensible, allowing for better sidechains and better lightning network plus fixes malleability and allows for other extensions to the protocol in the future. It also includes a small capacity increase, this was added to buy us some time until LN leaves it's current alpha stages.
Medium term: Lightning network, which will allow txes under 0.042BTC to be transacted off-chain instantly with very very low fees. They can still be transacted on chain if wanted however. Currently microtransactions are not possible, LN fixes that. LN is also optional, you do not need to use it.
Long term:
1. IBLT/weak blocks will decrease bandwidth and RAM requirements for nodes, making increasing the limit safer. Extension blocks can be used to increase the limit.
2. Sidechains. A sidechain of MimbleWimble will allow Bitcoin to scale to visa levels. The entire blockchain of MimbleWimble never grows bigger than 1MB. Additionally MimbleWimble has the best privacy features of any cryptocurrency in existence.
Only increasing the blocksize limit is not a long-term solution to scalability. Currently a node requires at least 300GB bandwith/mo. Doubling the blocksize icnrease this by more than double. Over time, running a node will become so difficult that there will only be a few nodes, leading to centralization. SPV wallets have no privacy at all, all your transactions are known to the node. Those few nodes could be forced to censor transactions, spy on users or even be shut down. Additionally the largest blocksize the current code can support is 72MB, not nearly enough for visa scale.