I don't think you can blame all of Toys r Us's problems on online competition. There seem to be more places to buy toys in an average city now than there used to. The Entertainer and Smyths have good sized shops, full of bright exciting things, tailored to the kids market - in comparison to the sterile warehouse that Toys r Us offers- it feels like it's still stuck in the '90s.
Plus there are decent toy selections in large supermarkets, there are Lego shops in most large metropolitan areas (though not Birmingham IIRC), even shops like Waterstones sell some toys nowadays - buying physical toys in a physical shop is still happening - it's just that Toys r Us got lazy, tried to keep offering the bleak aircraft-hanger sized places in retail parks that were sufficient twenty years ago.
Some shops can be boring - I don't go to B&Q for charisma - I'm happy to accept dull aisles of practical things - I accept that a simplistic minimalism can even be a selling point at somewhere like Lidl (i.e. you design the place to look deliberately "budget")... but toy shops should be exciting places of discovery - and most toy shops still are - they know that you are buying into more than just a physical product - they can be a "destination" shop - it's just that Toys r Us remained offering a functional warehouse instead of somewhere that you'd *want* to go.
Toys r Us reminds me a bit of JJB - which was a sports shop but it wasn't the cheapest sports shop (Sports Direct), it didn't have the largest range (Decathalon), it didn't provide specialist help (e.g. Up And Running), it didn't aim for the premium shopper (e.g. Blacks) and it didn't really cater to the trendier end of the market (JD). It was just a middle of the road shop - and so wasn't going to be anyone's first choice.
Maplin, on the other hand... I'm sorry to see it go, but I could never work out what it's main purpose was. Not a DIY place (e.g. Screwfix), not a "big box" place (e.g. Currys), not selling anything particularly expensive (e.g. PC World), half a foot in the "gadgets and boys toys" market (that other places did better - e.g. most malls have something better). They sold a lot of things that Poundland flogged cheaper (batteries, phone chargers), they were good for the kind of "projects for school kids that would get them interested in building a rudimentary robot" but it never seemed like much of a business model.
I liked Maplin, in the way that I like Richer Sounds (passionate staff who talk to you like a human being) but at least I can spend a couple of hundred pounds in Richer Sounds (on a telly or a sound system) which is where they make their money. With Maplin, it felt like a useful place for little things that never added up to somewhere that would make enough money to survive in the long term.
(but the easy answer will be to blame Amazon etc, so that's what the headlines will focus on)