Bitcoin is as fast or slow as it always was. Transactions never were reliable before they were included in a block. In fact, Satoshi suggested to wait for six confirmations before accepting a payment as fact. I concede that the price of blockspace has increased significantly compared to earlier times. However, this is all of our fault: collectively, we, the Bitcoin users find blockspace valuable enough to pay the currently required transaction fees to get our transactions included in blocks. And we collectively, have not changed the consensus rules to increase the transaction capacity, yet.

Speculating on what Satoshi Nakamoto would think about that is subjective, irrelevant and distasteful. If Satoshi Nakamoto wanted it to be known what her thoughts on anything are, she could very easily provide a message signed with a corresponding private key. It seems that either she does not want to argue from a position of authority, or that she has moved on to other things. This leaves us with the neat situation where we can and should make up our own minds, on basis of the merit of the arguments provided about topics.

Now, judging from the way you have phrased your question, it seems to me that you want to put the fault squarely on the Bitcoin Core developers' shoulders. Firstly, this is an arbitrary subset of the people that are at fault, not only because there are a number of different node implementations that make up the Bitcoin network and thus contribute to the enforcement of consensus rules in the network, but more importantly because this is an arbitrary minuscule subset of people that have an opinion and influence on evolving consensus rules of Bitcoin.

In fact, the Bitcoin Core contributors have worked hard for several years, not only to provide multiple hard fork proposals but also to provide the Segregated Witness soft fork proposal which has been ready for activation since last year. So, perhaps you mean to ask: "why has the Bitcoin community not adopted any of the numerous proposals to increase the transaction capacity, yet?" or perhaps "will rising transaction fees cause the Bitcoin project to fail?" or "if a limited transaction capacity is the central problem of Bitcoin's advancement, why hasn't anybody successfully hardforked the Bitcoin network to consensus rules that provide a higher transaction capacity yet?".

This question provides a good cross-section of everything that is wrong with the Bitcoin scaling debate. It blames an arbitrary subset of those involved. It includes several logical fallacies. It fails to take responsibility. It is not interested in learning, but in assigning blame.

There are numerous individuals, companies, groups, associations, services, foundations and committees providing input on what Bitcoin is, what Bitcoin means to them, and what Bitcoin should be. Fact is, that there are multiple divergent visions on how to advance the Bitcoin project. If you're interested in a comprehensive and balanced discussion of what the most important properties of Bitcoin are, why and how we would want to increase the capacity of the network, and how to achieve any vision for Bitcoin to come true, you should try to take a few steps back and ask a more open-minded question.

Disclosure: I have contributed to Bitcoin Core. I've also contributed hundreds of hours curating content on this knowledge platform in order to help people better understand Bitcoin, and facilitate knowledge transfer from experts to novices without undue burden on experts. There are more than enough platforms to discuss the politics of Bitcoin. There are too few platforms that facilitate learning. As per our community guidelines, I will strongly oppose rude, abusive and speculative content that aims to politicize or poison this platform.