It just happens to also be the case that the design Satoshi had for payment channels at that time was horribly broken and left nodes open to DoS attacks. So it was removed by other developers and slowly over time safe versions of the features were added again in the form of BIP68 (sequence number transaction replacement) and BIP141 (segwit).
And large blocks were very much part of Bitcoin's original plan. They were described even before the initial release of the software:
It's strange thing to try to summarize something and have someone question it happened at all. The subtext of this confuses me. This is a public mailing list and most of the people are still around and can answer much better than I can why the design of the opcodes are the way they are. There have been surprisingly many blind alleys in the short life of Bitcoin.
Payment channels are what Satoshi advocated, but it was my impression at the time that many others were more interested in things like sidechains and bearer proofs. The scalability of a system where everyone stores everyone else's transactions for all eternity was and still is the first thing people comment on. The second is the feasibility of everyday payments when the recommended confirmation time is up to an hour, best case. That's the reason people took interest in these proposals, even at a time when there was no economic pressure to do so, as transactions were completely free.
There's was no "original plan" as much as there were discussions. That doesn't mean Satoshi didn't have opinions. If your impression of the block size is shaped by the carnival mirror that is Reddit, it might be interesting to look at the reasoning why this limit was kept in place. But none of that matters in practice right now, because there is overwhelming consensus to double the block size (or quadruple, thinking adversarially) in a backwards compatible way and this will be active in a matter of weeks.
I didn't say that. I said there was no code added with the intention of making payment channels possible. The claim that there was is based on nothing more than conjecture on what the intended purpose of the script was, and the dating of an undated email from Satoshi that was first made public in late 2013.
>There's was no "original plan" as much as there were discussions.
There were multiple statements by Nakamoto explaining how Bitcoin could and would scale. This was widely understood to be the scaling plan, as evidenced by what the Bitcoin Wiki said about scaling all the way up to late 2014. 
It's odd for you to describe your conjecture about the intended use for op codes and data fields as facts, while dismissing clear statements of intent by Nakamoto regarding how Bitcoin would be able to scale.
I merely summarized some of the many discussions that took place on a mailing list a few years ago. There are several pointers to notable posts in the wiki, and the archive contains all the source material.
If you or anyone else were also present in those discussions and wishes to analyze what was said and what could have been, I'll gladly take that discussion private. But I'm not interested in discussing the equivalent of whether the moon landing was staged.