And AFAIK, nobody in Britain expected submarines to be a threat, which was the point.
Actually the loss of obsolete ships in WWI usually has more to do with the rapid pace of tech advances of the decades prior (many of them weren't that old when WWI broke out but were already obsolete) while the expense of constructions & limited dockyards meant that there was no way of refitting the masses of older vessels to new standards. So they get the short end of the stick.
And those are the things I had hoped to change, for a start. Going from a "torpedo gunboat" to actual destroyer need not have taken so long.
It didn't take long for the "torpedo boat destroyer" to also take over the role of the torpedo boat's role of launching mass torpedo attacks against enemy fleets. The existing torpedo boats just hang around because navies tend to not throw away things unless they're really shitty (note the sheer numbers of armored cruisers & pre-dreadnought battleships remaining at the start of WWI, though the bulk of them being in secondary roles)
IMO, that's true, & that's something that could have been bypassed (it not eliminated). The "gun club" mentality doubtless hampered development of torpedoes, & so development of DDs & subs.
Actually there were a lot of development poured into torpedoes and related development from the late 19th century onwards, precisely because a lot of countries (specially the ones with smaller navies & budgets) wanted a cheaper (and faster) way to equalize the field against traditional battlefleets. Despite their hopes and dreams reality didn't pan out that way.
One of the biggest hurdles was the have the ability to have small, highly maneuverable vessels... that are also capable of operating on the high seas. Those 2 needs are kinda mutually exclusive, but it sure as hell didn't stop countries from trying. Just look at this:
It's basically a steampunk Cylon basestar (in terms of designed role, as in a vessel that relies on launching smaller vessels to do most of the attacking). Idea didn't really work out in practice but it showed that countries were willing to spend quite a bit in experimenting with torpedo and related developments.
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Now for an actual bit that might be dealt with hindsight was the development of British destroyers of the 1890s to early 1900s, in which OTL development was obsessed with top speed on trials (which turned out to translate into jack shit in actual service as conditions in the North Atlantic did a number of those vessels as their speed tend to drop significantly in rough conditions, '+30kts' on trials quickly turned into 'less than that of the battleline and they need to turn back before being swamped by the waves'). Of course that would also have to educated the public (public opinion of the time only concerned with paper specs... actually nothing has really changed from then). That being said there's a problem:
-good handling in rough seas require high freeboard
-high freeboard increase weight
-increase weight requires more powerful engine
-more powerful engine requires larger hull
-bigger hull increase expense
... and the cycle continues, its really difficult to find a balance (except increasing displacement, which is pretty much what happened OTL).