It’s not just your impression. It really is harder to lead the US government today. Trump is in the news bashing the Freedom Caucus. But the inability of the House Speaker to pass bills is not just personality or talent. It is structural. In the “old days” before Nixon, the Speaker of the House had significant power over the rest of the legislature. He (it was always a he back then) could make or break the careers of individual Representatives. The levers of power were the ability to appoint and dismiss committee chairs, to direct funds to various districts (earmarks), and provide funds for reelection. None of these levers are what they used to be. Committee chairmanships are far less valuable (more on that in a minute), earmarks (which were never much over 2% of the federal budget) have been formally banned, and party-directed reelection funds are less helpful post Citizens United (since there is so much more outside spending now). In short, the House Speaker can neither threaten nor bribe other members, and thus has no leverage. He or she is reduced to “first among equals” and mainly has the power to schedule or not schedule bills, but not the power to sway the votes. And it is only in this environment that 31 members can shut down a 435-member body.
Before the reforms on the 1970s, committee chairs were much more valuable, because committees met behind closed doors, and chairs could get their way more easily. It would sometimes happen that members of the committee would come out of a closed-door committee vote all claiming to have voted against, even though the bill passed committee. Why? Because behind closed doors congressional leadership could do quid pro quo horse trading, and a lot more compromising was possible. Proponents of government transparency were aghast, but the system functioned well. Then came the “Sunshine Laws” and now every vote of every member in every forum is public. Which sounds like a good thing. But it has mainly functioned to make single-issue interest groups (like the NRA or Anti-Abortion groups) more powerful, since they can now detect and punish every minor digression. And since Republicans tend much more strongly to absolutism in their thinking, it has become a huge problem for that party. Maintaining a 100% rating from the NRA, or from Americans for Tax Reform, becomes essential for surviving the primaries. But it also makes compromise, even within your own party–much less across the aisle–impossible.
Earmarks are provisions allocating specific sums of money to specific projects. They are usually tacked on to bigger bills, and do things like direct money towards a museum in one district, or towards an public rec center in another. At their height they never went much over 2% of the total budget. They allowed Representatives to show the voters back home that they were working for local improvements. And they were also the main means of winning support for big national projects that needed broad support. But they are largely gone now, a so the House Speaker has a much harder time winning over reluctant legislators to a big bill.
Finally, when campaign money had to be won in $1000 increments from as many different people as possible, $1 million from the national RNC actually meant something. Today a single billionaire can support the career of a pet politician more or less indefinitely. For Representatives with this kind of support, there is little the national Party can offer or threaten to sway support for a given bill. Being Republican becomes more about identity and brand, and less about being part of a team that needs to work together for any of its individual members to succeed.
So it really is next to impossible to be the Speaker of the House today. It is a high visibility position with almost no levers of power.